str_replace username

[woostar]

Hi there,

Hope someone can help. I'm trying to add tracking to certain links in Vb.
Assuming that the below code was in a new php file, what would I have to 'include' / add to the code below to make $username = username (if that makes sense).

PHP Code:

<?php

$url = str_replace('[TRACKUSER]', $username, $url);
header('Location: ' . $url);

?>

Regards,
W.>