iPhone 3gs unlock for use overseas

[brex480]

ill make this fast because i don't have much time online. Im in the army and will be leaving for Germany this summer. I am wanting to know if my 3gs will work overseas and how well. i plan on switching to t mobile so my question is what all do i need to do to get the phone set up over there and data working(will 3g work)? im not new to jailbreaking but have never done an unlock before so any help would be great

3gs
3.1.2
5.11.7
jailbroken w/ blackra1n

[mavrik101]

Follow the tutorials on this site. Just download some software and youre there.