To the OP, countless threads on JailbreakMe.com have been posted (namely a stickie), as well as a stickied guide on first-time jailbreakers, for help with Cydia, and adding repos like hackulo.us.
Originally posted by applepod
If he's on 4.0.2 he needs to downgrade as the PDF exploit is patched.
Spot on, OP doesn't know what he's talking about :p
Originally posted by Revo
It shoulnt..Jailbreaking is now legal..But if it breaks just break it more so apple cant fix it!
Yeah Revo, jailbreaking may be legal in some countries but Apple still voids warrantee regardless.