Adding a function to a vbulletin page?

[kpf1827]

I am trying to add a php function to my template... I made a script in PHP and put it in a file called "script.php" on my server.

Now Here is the problem, how can I call this function on the page, so I can use it? How does vbulletin currently call other functions? BTW this function will be used within the navbar. I cant use a HTML script because it will only work after the page fully loads up. What are your suggestions. Thanks!