Hopefully you will not be playing via wireless connection…
In the Port range forwarding menu, make one entry for each of the following:
starting 7845 ending 7845 UDP
starting 4398 ending 4398 TCP
starting 4000 ending 4000 TCP
Enter your ip address at the end (i.e. if your IP address is 192.168.1.105, then enter 105 in the last box). If you don’t know your IP address, click start->run, type “cmd”, hit enter, at command prompt type “ipconfig”. The first value (192.168.1.xxx) will be your local IP address, as assigned by your router.
Click apply after entering each line, then click save at the bottom. You don’t have to enter anything in the “application” field, as it is there strictly for reference.