Need help to find someone's IP.?

I don't unerstand this completely. If you don't want him to contact you why in the world do you keep chatting with him? Furthermore if it's his IP address you want I ume you want to turn him in to make him stop contacting you. The first step is to contact Yahoo and tell them what is happening. They will in turn start monitoring your activites and locate this person. If you reallly want to get serious and stop this person from "harring/stalking" you, you can always take it to the police deparment and speak to a "cyber" detective. Most police departments have officers who in fact can deal with Internet activity. I ure you they will find out who he is but you are going to have to make a charge and stand by it.