If you look under "Edit Your Group Profile," there's a section that says "Optional HTML" where there are two fields that you can paste the codes for backgrounds, etc., into.
There is a limit to how long the codes can be, but I'm not sure what it is. It might take a few tries to get it perfect.
I know, but whenever I try that, it doesn't show up. I want to put a picture as backgrounds and when I see groups with that it says animation station, but I can't find anything there! i better look some more