Any Flickr shot that can be downloaded in a medium resolution works fine as a background. There's a huge range oof photos tagged as 'wallpaper' for starters.
You can do this yourself with your own pictures. Just resize one to 500 pixels wide and 300 pixels high. Most any photo software should be able to do this. If you need a freebie, download IrfanView. Save the resized picture, connect your IT, or your memory card, to your computer, and transfer the picture file to the card. Then on the IT home screen. tap the bar at the top, select "Set background image..." and browse to where you saved the file. Select the file and click OK to install it or Preview to see it.
