[nmglug] port forwarding

Persons of the nmglug; On one computer I have UDP ports 5198-5199 opened and TCP port 5200.and it works On the second computer I wish to place the same ports.can anyone supply specifics? 1.)Have not fooledl with "the try it and see experimenting" am not certain where to place the firewall exceptions or if they are necessary to place manually. 2.) a seperate recent port forwarding experience the portwas already occupied and could not be used,althought in this instance it was on the same computer, and not on two computers as the question is posed today. The connect is dsl, router xyzel pk5001z. Best,a