Hey man,
I was in a similar situation a few days back but got helped out and read up on it. Basically I wouldn't bother jailbreaking your phone if you have the newer bootrom.
Basically if you have the old one then you can jailbreak it....but...If you have the newer one then you can only do what's called a tethered jailbreak which is like a normal jailbreak but if your phone runs out of battery or crashes and you need to restart it then you can't wake it from sleep without a computer, a usb cable, and a copy of blackrain.
So I'd advise you to first find out what bootrom you have

you do this by putting your phone in DFU mode:
http://www.iclarified.com/entry/index.php?enid=1034
once it's in DFU mode do the following:
on PC:
Start->Control Panel->Device Manager
In Universal Serial BUS Controller, you will find Apple Mobile Device USB Driver
Right Click and go to Properties, go to Details tab and select "Device Instance Path" from the drop down list box.
In that information, u will find [iBoot-359.x] at the end.
on mac
Click on your HD > Applications > Utilities > then System Profiler
From there look in your USB serial Bus bit and you should find it there.
(obviously your iphone needs to be connected, I know that a bit pointless mentioning but you never know who might not haha!)
When you have found out what your boot rom version is post it here and I'll try and help you some more