Fixed it,

<?php
 // Add these lines in the very top of your code
define('FORUM_ROOT', './punbb/');
require FORUM_ROOT.'include/common.php';
if($forum_user['username'] == "Guest"){ echo "Hi Guest"; }
else echo $forum_user['username'];
?>

Hi,

It seems that the avalible codes aren't working with version 1,3.

How to show users username outside forums?