eh, I can help you up to a certain stage but not much more than that (as I have bt, which portfowards in a different way.)
first, click on the start button and type 'cmd'. open the one which has a blackboard icon.
then, in the cmd thing type ipconfig, and then enter, and it should come up with a bunch of ips.
you need to find the default gateway which is at the top.
thirdly, you need to copy that into the search bar, and then I can't help you any more unless you have BT.