Same as what the others have said.
Here's how you do it.
1) Right click the 2 little monitors icon (wireless network connection )in the right corner of the screen and select "Status"
2) Under the "support" tab write down the numbers for IP address and Default gateway.
3) type the default gateway number into your address line of your internet browser
4) the username and password are the same: admin
5) select the applications and gaming tab
6) in the 1st line type in
applic start end protocol ip address enable
------ ------- ----- ----------- -------------- ---------
anyname 6881 6999 tcp xxx.xxx.x.___ check
the last three numbers of the ip address should match the ip address that you wrote down in step 1 (the address for the computer that you want to forward these ports to).
If you are running norton internet security you will have do something similar in that program as well.
Josh