Do you mean the 4S? I'v written a hub about jailbreaking here: http: // wookiewonderfuls.hubpages[dot]com/hub/Jailbreaking-An-Iphone-The-Pros-and-Cons (without spaces and a dot where [dot] is)
It doesn't tell you how but it does tell you the pros and cons.
I wouldn't recommend jailbreaking a 4S as its so new, if you jailbreak you immediately void your warranty which is something you really need as its so new.
If you would like further info inbox me :)