<?php

/**
 * @author Jason
 * @copyright 2011
 */

if ( $_POST['submit'] ) {

    $username = $_POST['username'];
    $password = $_POST['password'];

        if ( $username && $password == "jason" ) {

            echo "Works!";

        } else {

            echo "Wrong!";

        }

    } else { ?>

    <form method="POST" action="">
        Username: <input type="text" name="username"/>
        Password: <input type="text" name="password"/>
        <input type="submit" name="submit"/>
    </form>

    <?php
    }
    ?>