Custom Background Image

I just purchased a custom background image. It does not seem to be showing up. I read the post at the top of this forum, and followed those upload directions to a T. I am relatively certain there was no typo in the window in which i purchased it. Is there any way to see what filename i chose to use as my custom background image, so I can double check? Has anyone else had trouble with a newly purchased image not working?

Your file had a ".JPG" extension, but you entered ".jpg" in the store.