Pleasse Help

Hi, I am working in Iraq and I am computer iliterate, I have no idea how this stuff works, but I do like myspace its a good way to keep in touch with people. My wife is on there and I got same very disturbing messages. They are from a fake address and have emails back and forth from my wife to another man. I have my idea who it is but

I need to be able to ***** that persons IP address and the fake ones and find out if it is coming from the same computer.

Please Help Me I need to know.
Thank you very much