Open a web browser like internet explorer or Netscape. Enter the ip address of your router in the address bar of your browser. In the picture above the address bar has http://www.google.com in it. Just replace all of that with the ip address of your router. By default the ip address should be set to 10.0.0.138.
When you are finished, click the Done button at the bottom of your screen. And that is it! You are done!