Right now i would wait alittle, a new jailbreak is going to come out untethered for 3g by geohot so. He is probably waiting for the new firmware to come out first. If you can't wait there are some videos on how to do tethered jailbreak on youtube
It is ok if it is jailbroken but teathered please give me some links.....
Also the link needed to reboot it if it does switch off or run out of batteries....
It is a brand new 3gs never been jailbroken before....