To get a background picture you have to upload it to a profile album. To create an album to just for your profile or just pictures in general, this should do it: http://forums.khinsider.com/album.php?do=addalbum
Or, alternatively, go to User CP, and under the Networking heading, click the Pictures and Albums option, follow the link, and add an album in there.
Or, alternatively, go to User CP, and under the Networking heading, click the Pictures and Albums option, follow the link, and add an album in there.