and i have more than one class

this is my java file and im using netbeans

import java.applet.*;
import java.awt.*;
import java.net.*;
import java.awt.event.*;
import javax.swing.*;
public class sb extends JApplet  {
    Thread threadABC;


AudioClip gong;
    /**
     * Initializes the applet starbucks
     */
    @Override

    public void init() {

        resize(920,700);

        /* Create and display the applet */
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    gong = getAudioClip(getCodeBase(), "/Users/haneenmegren/NetBeansProjects/starbucks/build/classes/my/song.wav");

                    gong.play();



                    initComponents();


                }
            });
        } catch (Exception ex) {
            ex.printStackTrace();
        }


    }

    /**
     * This method is called from within the init() method to initialize the
     * form. WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */

    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jButton1 = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        jButton2 = new javax.swing.JButton();

        jPanel1.setBackground(new java.awt.Color(0, 0, 0));

        jLabel1.setIcon(new javax.swing.ImageIcon("/Users/haneenmegren/Downloads/new.png")); // NOI18N

        jTextField1.setBackground(new java.awt.Color(59, 48, 39));
        jTextField1.setFont(new java.awt.Font("Lucida Grande", 1, 13)); // NOI18N
        jTextField1.setForeground(new java.awt.Color(255, 255, 255));
        jTextField1.setText(" ");
        jTextField1.setBorder(null);
        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });

        jTextArea1.setBackground(new java.awt.Color(59, 48, 39));
        jTextArea1.setColumns(20);
        jTextArea1.setForeground(new java.awt.Color(255, 255, 255));
        jTextArea1.setRows(5);
        jTextArea1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 102, 51)));
        jScrollPane1.setViewportView(jTextArea1);

        jButton1.setText("SEARCH");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jLabel2.setIcon(new javax.swing.ImageIcon("/Users/haneenmegren/Downloads/starbucks_by_lovecupcakexx-d51w1sy.jpg")); // NOI18N
        jLabel2.setText("jLabel2");

        jButton2.setText("WATCH");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 919, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(64, 64, 64)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 414, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton2))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 261, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 269, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING))
                .addGap(112, 112, 112))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 194, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(56, 56, 56)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 44, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addComponent(jButton1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jScrollPane1))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addComponent(jButton2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel2)))
                .addContainerGap(154, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
        );
    }// </editor-fold>                        

    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                           

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         

       try {
        String urlString = "https://www.youtube.com/watch?v=CBm7Ata6Q_Q";
        Desktop.getDesktop().browse(new URL(urlString).toURI());
    } catch (Exception e) {
        e.printStackTrace();
    }

    }                                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
   try {
        String urlString = "file:///Users/haneenmegren/NetBeansProjects/JavaLibrary10/build/draw.html";
        Desktop.getDesktop().browse(new URL(urlString).toURI());
    } catch (Exception e) {
        e.printStackTrace();
    }


// TODO add your handling code here:
    }                                        




    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration                   

    private void getAppletContext(String usershaneenmegrenNetBeansProjectsJavaLibr) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    }

and this is my html file

<P>
<APPLET codebase="classes" code="sb.class" width=970 height=700></APPLET>
</P>

and the html inside the bulid folder and the classes to

teh code is working here.Does it has error when you run it?

the code is working here.Does it has errors when you run it?

no its show only gray backgrond on the browser