WHEN CHATTING ON YAHOO MESSENGER SOMEONES DISTURB OR INSULTING ME, OR
LIES ON THEIR HOME COUNTRY, SO WITH THERE IP I CAN TRACK THEM AND WILL
KNOW FROM WHERE ARE THEY CONNECTING TO YAHOO. THAKS

Unfortunately, users using Yahoo Messenger connect to a central
server, thus one user can not see the IP address of another.  You can
see their IP address, however, if you enable a direct connection with
them (i.e. send/receive a file).

You can set up a fake webpage on a webserver somewhere, give them the
link to it, then check your referrer logs for the ip.

Get a program like Tiny Firewall (available at download.com).  This
program uses mirror firewalls to display the person's IP.  Sometimes
you can get a person's IP when they message you.  It seems to work
best if the Yahoo messenger and the firewall program have just been
started.  If you send them a file, you can quickly get their IP.

If you use Tiny Firewall, disable the firewall, or else you will have
problems with YM and other programs.

If you've managed to obtain the person's ip address there is a product
out there that produces a map image of where there isp is located,
which is usually around the area of where they are, unless they are
routing through different ips, which is stupid if you're just gonna
bug people on yahoo. as the other comments say on here on how to
obtain the ip address, this is how you track it. with NeoTrace. it's
not a cheap program, but if your that willing to track down your
assailant, then this is how you do it.
I do not condone violence for this situation, nor do i condone piracy
for the acquiring of NeoTrace.