help needed iphone 3gs 05.16.01 ios 4.3 8f190 at&t

Please help me with my Iphone 3gs 05.16.01 ios 4.3 8f190 at&t?
What is the best way to unlock it?
Thanks
R

Please search before you post. This question has been asked hundreds of times. You are unfortunately not in a good situation, the only solution is to upgrade to the iPad baseband and this carries serious risks and may disable your GPS. It will also impact how you restore your phone for the entire rest of its life. Read up on it at the dev-team's site or search the forum for more posts detailing this process.