i want wallpapers that are appropriate, free, and that i can download instead of right-clicking and saying "set as background" because it won't work on my computer

deviantart.com is always a great place to look. it's free and there's a wide range of categories and artists.

Go onto the Yahoo! Search Engine- or Google, whichever- and put in 'free abstract wallpapers', quite a few should come up. If you want appropriate one then just miss out the ones that say stuff like 'hot babe wallpapers!' or 'Hentai wallpapers', 'cos they probably ain't what your looking for!

image search abstract wall papers or backgrounds-- right click them at full size and save them to your computer.