Internet/Router Connection for multiple users

Hope that someone happens to know about these technique stuffs.

The broadband was activated in my flat this Wednesday. My flatmate did all the router (Netgear DG834G) logging in and internet setup, and he could access the internet immediately, unfortunately, I can't. As I ran the ipconfig, it seemed that I got IP address, DHCP, DNS. But there was nothing for "default gateway". I figured that might be the reason. Does anyone know that whether I or my flatmate should reset anything?

Many thanks.