/*  Index.html  */
<form action="login.php" method="post">
	<input type="text" name="username" /><br />
	<input type="password" name="password" /><br />
	<input type="submit" name="submit" value="Login" />
</form>

/*  Login.php   */
<?php
	$username = $_POST['username'];
	$password = $_POST['password'];

	if (!empty($username) && !empty($password)) {
		echo "You entered username:" . $username . " and password:" . $password . ";
	}
	else {
	    echo "You have left a field empty.";
	}
?>