Finding ip using user id

Hello,
Hey people plz help me anyone.
i hv a user id no like 1770582713. now i hv to find his ip address.
he is making a lot of trouble to me. so i heart frm some 1 if i can get his user id
i can easily find his ip address through a chinies software and it works like
keygan. if i write the user id no on tht prog it automatically shows the ip whn tht user will
logged in nxt time. but i dont know the soft name.
so plzz help with this if thr is other ways thn let me know.



and give me a good site name where i can find free hacking soft