<php
$username = $password ='';
?>

<form action = "login.php" method = "post">
<input type = "text" name = "username"></br>
<input type = "password" name = "password">
<input type = "submit" name = "login" value="LOGIN">
</form>
<?php

if (isset($_POST['login'])){
if(($_POST['username'] == 'admin') && ($_POST['password'] == 'password')){
header('LOCATION:index.php');
               }
else {
echo 'ERROR: Invalid username and/or password.';
}
}
?>