How do i signup for ps3 network ?

May be...

i cant sign up because i live in THE BAHAMAS.i have to choose where do i live.but they dont have the bahamas to choose.

I hadded the same problem as you cuz i was living in another country! I just selected us and the hard part come up! U need to put VALID postal code and street adress of what country u selected or it wont accept it! i just writed there New York i googled New York streets and then i found one website with streets! i just putted in 2 or 3 diferent streets and it worked! Follow the steps that i've done!

Just choose somewhere near where you live. You won't get banned since it's Sony's fault for not giving the place where you live an option.