As far as I know, there's no reason to change "Port", whatever number that is there you should probably just leave alone...what you will need to do is enter an IP address to connect to...
Let's say your friend is trying to connect to your computer (so basically, you are the host)...he will need to enter in your IP address to connect to the game you are hosting...
In order to find your IP address, run command prompt (either enter "cmd" in the windows "run" utility or open up command prompt under accessories)...once command prompt is open, type "ipconfig"...
Most likely, a lot of information will pop up...what you want to find is the heading "Ethernet adapter Local Area Connection" or something similar to that...listed under that should be several addresses...IIRC the one you want is usually labeled "IPv4 Address"...I could be wrong though, so if that doesn't work you may need to try some of the other addresses (like "Default Gateway")...
Anyway, if your friend enters in your IP address then he should be able to find your game...it's important that you are actually on a Local Area Network, and not simply trying to connect through the internet...