Anyone bored enough to help a clueless, idiotic fellow blogger?

OK...I have tried for the fifteenth time and I still can't get the background on my blog changed (isn't anyone else tired of the brown and pink stars?). Anyway, I found a cute fall background...couldn't get it to work. Found a cute winter background...nope - no can do. And now I have found a Christmas background that for the life of me I can't get to show up on my blog page. Everyone else seems to be able to change their background without difficulty. In fact, I have come to believe that a few of you may even be rubbing it in a bit (way too many cute background changes happening). SO, I am ready to confess. I have officially developed a complex about the whole thing. I had no idea until now (well maybe I suspected it) that I was mentally handicapped. If anyone out there is bored enough to clue me in on the "secret" of changing a stupid blog background - I am ready to go. HELP!