Mac OS X 10.5 Help
Using AirPort to connect to the Internet
If you have an AirPort card installed in your computer, and you are in range of an AirPort network that is connected to the Internet, you can use AirPort to connect to the Internet.
To join an AirPort network:
Choose Apple > System Preferences, and then click Network.
Click AirPort in the network connection services list and choose a wireless network from the Network Name pop-up menu. Enter the password for the network if necessary.
If the network you expected is not in the list, it may be a “closed” network and not be available in the list. Try clicking Other, and then enter the network name and password if necessary.
If AirPort isn’t in the list, click Add (+) at the bottom of the list, choose AirPort from the Interface pop-up menu, give the AirPort service a name, and then click Create.
Select “Show AirPort status in menu bar” to display the AirPort status icon. You can use the AirPort icon in the menu bar to choose your network from the list and connect to it.