Attack Detected

My firewall continually pops up with a little message saying that an attack
to some port was detected. It gives me some numbers (like that's supposed
to mean something to me) that I don't understand. There's a log with long
lists of these "attacks."
Am I supposed to do something with this stuff? How do I find out who the
attacker is?
As you can see, I'm not very experienced with firewalls (except for
shutting them off).