I have designed login page with html. if i enter credentials if it doesn't match then it should show error message in login page like invalid email or password.(no pop up). for this i should code in html. please provide me code. And if credentials match it should redirect to next page is landing page how to show welcome message with firstname lastname(already stored in thee databse) using html code.?

<html >
     <title>Help</title><link rel="stylesheet" href="css/responsee.css">


                     <form action=""  method="POST">
                        <div class="s-12 l-7"> 
                            <input type="text" id="user" name="user" required/></div>

                 <div class="s-12 l-7">

                     <input type="password" id="pass" class="masked" name="pass" required/></div>

                    <div class="s-3 l-7">
                     <button type="Login"  id="btn" >Login</button></div>



You're asking server side logic 101 here...

You can make the login page the same page that processes the login, have the form post to itself. On success, redirect, on failure post a message inline to the page.

You can use AJAX and send data over the wire, and return a redirect.

So many ways you can do this.. try something, get to a point you cannot go further, and then come back.