Your netbook should automatically detect the wireless router, so all you should need to do is enter the encryption key to access it, (WEP or WAP), then it should connect automatically.
My hunch is he has not enabled WEP or WAP since, up to now, he apparently has not used the router for wireless connectivity. Wireless broadcast might even be disabled in the router; actually, it should be if he has not been using a wireless device.
Assuming WEP or WAP is not enabled and wireless broadcast is not disabled in the router's control panel, you should be able to do as patio said. Then, I'd enable WAP to secure your wireless connection from any intrusion from outsiders.