Doesn't work how?
Does your network show up in the list of available networks under Airport?
What does it say under Sys Prefs > Network > Status: Airport? Is airport enabled?
Are there security settings set on the router that might make it difficult for airport to find it automatically (eg MAC filtering, SSID broadcast off)?
If the SSID (the network's name) is not being broadcast it won't show up in the list of available networks under the airport icon in your menu bar (presuming it's showing up there?) and you have to choose "Other" from the drop-down menu and enter the network name (and any security settings like WPA and password) manually.