How to share session with VBB?

[AllanSun]

Hi all:
I'm think of building a web site based on VBB forum.
My first problem I faced is that I can't use session from VBB.
For example, I put a URL from VBB page link to one of myself page.

PHP Code:


<?php
session_start();
if (isset($session)) {
  echo $session[userid];
}
?>

but it cann't work at all

otherwise, I serched the codes of VBB, but I cannot find any of the session functions appeared in them. Why? could somebody tell me where those codes are?