Assuming you're running Windows, hold down the Windows key, and press 'R'. This should bring up a run dialog.
Type in 'cmd' (without the quotes) and hit enter. This should open a terminal.
Type in 'ipconfig' (without the quotes) and hit enter. You're looking for the line that says "default gateway".
Open your web browser of choice (Internet Explorer, Firefox, Chrome, etc.). Type into the address bar the IP address that was displayed after "default gateway", which will follow the pattern 192.168.X.X.
This should bring you to the configuration page.