I followed this tutorial on my 3gs.

Jailbreak iPhone 3.1.3 with Sn0wbreeze | Redmond Pie

Apparently my iphone is Jailbroken but it is not unlocked and I would love to use my tmobile carrier with this device.

Please help, any suggestions?

Again, My iphone is only jailbroken, and not unlocked.

Thanks so much for the help.