How to unlock my iphone 4 on orange?

Hi guys i bought an iphone 4 on "orange" and want to use an o2 sim card i thought it was just the matter of taking it to a shop but i think its more advanced than that can any 1 help as is a birthday gift an hav to hand it over on sat Help?

Jailbreak it

You can Factory Unlock your iPhone 4 to use it with O2 Sim card.

This will help you
http://unlockappledevices.com/