Do you have the manual for your router? Most of the newer ones have easily accessible configurations, generally through a web page. You point your browser (from a computer connected directly to the router) to the router's internal IP address (if you can't find this anywhere, i would try 192.168.0.1), type in the user name and password (or just password depending on the model) that you've set up, and access the firewall configuration. You should be able to adjust the ruleset to open up the ports you need. Again, all this stuff should be in the router's manual, this is a very normal thing that everyone with a router needs to do on a regular basis, so I doubt the builder of the router would make it unnessesarily difficult.