Jailbreaking and unlocking your iPhone is not for the feint of heart. It has gotten relatively simple over the years (I've been jailbreaking/unlocking since 2007) but you still need to have fairly good technical skills and be able to understand just what it is you are doing.
One thing to bear in mind is that once you jailbreak/unlock, you have to be very careful about what updates you allow happen to your phone. As was stated earlier, if your iPhone has the most recent baseband/firmware, you are out of luck.