This is how I add a custom background to my profile page:
You must make sure the image you want to use is in a PROFILE
album. Pictures used for your Profile background MUST
be in a PROFILE
Double click your desired image. When it opens go to the text under Picture URL. Do a Control "A"
(Select all) then Control "C"
(Copy). You will now have the URL you need copied into memory.
Go back to your profile main page and click on Customize Profile
In the very first section you will see background image. Do a Control "A"
(Select all) then Control "V"
Select the Repeat function that works for your image. You may have to play with this.
Click the "save"
right underneath it.
Go to the very bottom and click "Save Changes"
. Make sure you save it in both of these places.
Go back to your user profile and your new image should be there. You may have to go back and play around with the repeat to make it work best for you.
Good Luck. I hope you can get it done now. The most common mistakes people make are not having their image in a profile album and not saving in the two places.