this is how you jailbreak an ipod touch or iphone. im not really sure which versions you do or do not have to have, all i know is mine is 4.2.1 and it worked on mine.
Step 1: First thing
okay, this jailbreak only takes a minute.
First, go into safari and type jailbreakme.com
Second, find the thing beside "Cydia" and it should be green and have "free" on it.
Thrid, double tap the free and it should install it like an app.
It takes about 10 seconds.
NOW U HAVE CYDIA!!!!!