C sharp connection error

[Galbatorix]

I have a class which connects to the db(sql server). I have a login class which authenticates the user away from the frmLogin form. Each time i click login, i get an error Executereader requires an open connection. I tried reversing the order of some variables but to no success.
here's the code for the connection class

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Albergo
{
    class Connect
    {
       public String connectionString = null;
        SqlConnection sqlCon;

        public Connect()
        {
            connectionString = "Data Source=SALITY-EXE\\PHILSOFTSQL;Initial Catalog=albergo;Persist Security Info=True;User ID=sa;Password=t3rminat0rz!";

            sqlCon = new SqlConnection(connectionString);
        }

        public Boolean OpenCon()
        {
            try
            {
                sqlCon.Open();
                return true;
            }
            catch (SqlException ex)
            {
                System.Windows.Forms.MessageBox.Show("Can not open connection ! " + ex.Message);
                return false;
            }

        }

        public Boolean CloseCon()
        {
            try
            {
                sqlCon.Close();
                return true;
            }
            catch (SqlException ex)
            {
                System.Windows.Forms.MessageBox.Show("Connection is already closed" + ex.Message);
                return false;
            }
        }


    }
}

heres the code for the Login

using System;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Albergo.Classes
{
    class Login
    {
        String username;
        String password;
        String sql;
        Connect connect;
        SqlConnection con;
        SqlCommand cmd;
        SqlDataReader datareader;

        public Login(String username, String password)
        {
            this.username = username;
            this.password = password;
            Connect connect = new Connect();
            con = new SqlConnection(connect.connectionString);
            sql = "SELECT * FROM users WHERE username = '" + username + "' and password = '" + password;
        }

        public int authenticate()
        {
          connect = new Connect();
            try
            {
               connect.OpenCon();
                cmd = new SqlCommand(sql, con);

                datareader = cmd.ExecuteReader();
                datareader.Read();
                if (datareader.HasRows)
                {

                    datareader.Close();
                    connect.CloseCon();
                    return 1;
                }
                else
                {

                    datareader.Close();
                    connect.CloseCon();
                    return 0;
                }


            }
            catch (Exception ex)
            {
                MessageBox.Show("There was a problem while trying to Connect: " + ex.Message);
                return 0;
            }

        }
    }
}

Please help me identify the error...

[Momerath]

In your second block of code, line 32 you create a new Connect object, but then in line 35 you open the connection with that object. But now in line 36 you try to create a SqlCommand object, but you use the connection in the con variable rather than the connect one that you just opened.

Your code is very confusing. You create an object to handle the sql stuff, then you add variables to hold all the sql stuff in your main code. Why would you do that when the Connect class has all that for you?

[Galbatorix]

I am using the logic of basic c sharp connection i found online. I am ajava developer who has just got into c sharp.