It says so in the instructions.

Quote: "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 Google in it. Just replace all of that with the ip address of your router. By default the ip address should be set to 192.168.2.1"

Quote: "You should see a box prompting you for your password. Enter your password now. By default your password is blank. Click the Submit button to log in to your router." ie: Don't enter anything in the password box, just press enter.