<?php
    session_start();
    $username = $_POST['username'];
    $password = $_POST['password'];

    if ($username == "zanacross" && $password == "lkjhm1") {
        $_SESSION['logged'] = 1;
    }
    if (!isset($_SESSION['logged'])) {
        echo '<form name="login" action="login.php" method="post">
        <input type="text" name="username" />
        <input type="password" name="password" />
        <button type="submit">Submit</button>
        </form>';
    }
    else {
        echo "You are logged in";
    }
?>