GAME PAGE HELP

How do I change the background of my game's page? I want it to loop horizonticaly and I already have the image in my locker. Can someone tell me the CSS code i need to use?

author=Kevincalanor
I don't really know how to work with CSS, but here's a helpful thread .on the subject ^^

I already read that thread. I did what it said but it didn't work. Does the site still have an issue with CSS?