For X reason you need to know your IP address. How do you find it?  Under Windows, go to Run->type 'cmd' without the quotes. Once you get to the command prompt ( black window), type in 'ipconfig' without the quotes again. Hit enter! You should see something like this :

In my case, 192.168.1.106 is my laptop's IP address. If I ever need to configure my router, I just type 192.168.1.1 on any browser and it will take me to a menu to configure my router.