How do i unlock 1g iphone?

[Sarah]

I have gone through the process of getting a working copy of 3.1.2 firmware, i have loaded it onto the iphone and i have used blackra1n to jailbreak it. According to all sources i should now have something called blacksn0w, found through blackra1n to unlock it but it does not show up on mine. I only get the option to install cydia and rock. I have tried this over and over again, using different sources for the software and still get the same results, what am i doing wrong? Please help or show me a different way to unlock it