UBB.Developers Forums Community Development Programming HTML, CSS, and JavaScript Background picture refresh

Hey every1!
I was surfing the net, and i've ran into this page: http://www.red-white.com/ - the second table of this page contains a backround with pics, each time you refresh same page different background pic is loaded (randomly, i assume). i really like this, and the question is: how do i do that kind of thing? because i can't find anything in their sources, maybe there is a seperet .js file?! or maybe something else?... But i dont know... Could you help me out?
Thanx!

real address is;

http://www.red-white.com/index.shtml

I think that they are using a perl script for random images & include it via SSI...

well, it doesnt really make i difference if you put a index.shtml

here is what i get:

that's all, and i cant figure out how to make the same background refresh? maybe you can give me some links where i can fins perl scripts?
thanx

The CGI Resource Index
HotScripts.com