how to include external thumbnail.php in homepage

[boatdesign]

I need to include("http://mydomain.com/thumbnail.php"); right below the private message/who's online and above the icons on the forum homepage (which builds a table of thumbnail images). But I can't remember how to get vbulletin to include the external php file in the correct location. Can someone give me a hand?

P.S. I thought that I could do this with templates and thus it was not "hacking" and therefore first posted this question over at vbulletin.com, but they said it was in fact "hacking" and needed to be asked over here instead.