There are over 300 pages of background you can search from.
If you don't like any of those, then I used to go to this one site, I can't remember the name of it though.
Your best bet is to either seach on google for premade layouts, or for picture of something you would want your background to be. Then copy the URL and paste it according to the directions on the link I gave you, here they are...
Find the background you want to use
Highlight the text in the box and use the Edit -> Copy or ctrl+C option to copy it
(for that step, copy the link)
Visit your column settings page. (be sure you're logged in)
Paste the background URL in the "bg1" or "bg2" option boxes and hit save. [ S_C's advice column | Ask S_C A Question ]
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