@natar (assuming you've created the respective files)

<?php
    $phpself = $_SERVER['PHP_SELF']; //its you php page.
    switch($_GET['id']) {
        case '1':
            include("home.php");
            break;
        case '2':
            include("home_2.php");
            break;
    }
    echo "<a href=$phpself?id=1>Login</a><br><a href=$phpself?id=2>forum</a>";
?>