go into image manager, click upload, upload the pic you want from your computer (make sure its not BMP) and then rename it my_background.jpg or w/e kind of file you uploaded. ciao tell me if it works.

well..i put it to this green one than i tried change it to a pink one the one i rly wanted but when i change it to my_background.jpg...it well doesnt leave!!! what the heck and i deleted it!