it depends what you mean by background. home screen background, im guessing? if you have an ipod touch 3g or higher (this is an ipod with 32 gigs or more) then you should be able to do this with the...
you have to find a background on your computer or ipod.save it.then go to pictures on your ipod. then touch the picture you want.then you will see it up close.so press the little arrow on the side...