I ve bought a Canadian iphone and i ve made the mistake of updating it last Mars (month). Now i am not being able to jailbreak it again.
1 How do I find out what version is my OS and Baseband.
2 How do i Jailbreak it?
3 How do I unlock it?

By this time i can log it into itunes but it just asks for a valid sim card and stays on the start screen locked.
Is there a reasonable way for me to fix it?

Thanks a lot. Kind regards. Paulo

1) TinyUmbrella can tell you what iOS revision and what baseband are on your phone.
2) Depends on what iOS revision you have.
3) Depends on what baseband revision you have.

In a lot of cases, you'll still need a legitimate SIM to pass the initial activation, but if you can use TinyUmbrella to get your iOS and baseband revision, we may have some better info.