getting itnernet at a friends house

Just a quick question.
When I used to bring my iBook G4 to my friends house, a message would come up saying "none of your networks can be found, would you like to join the network "(here it would name some network)?" And I would click yes and I would get internet. However, now I cant get internet at his house because no message comes up. How can I get internet there? I used to, so I know it can be done. Is there a way I can manually search and join a network?
Thanks!

Click the icon in the menu bar on the right that looks like waves. Once you click that a list of networks, if there are any in range should show up. Once you find his network, click on it and you should connect.