OS X Mountain Lion: Requirements for wireless Internet access
To use Wi-Fi to access the Internet wirelessly using OS X, you need:
An Apple AirPort Card, AirPort Extreme Card, or a compatible third-party wireless card
An AirPort Base Station, Time Capsule, AirPort Express, or a Wi-Fi-enabled computer acting as a software base station (if you are hosting an AirPort wireless network)
If you’re setting up an AirPort Base Station, Time Capsule, or AirPort Express to connect to the Internet, you need an account with an ISP. When you set up your account with your ISP, you were most likely given account information (such as user or account name, password, phone number, and possibly other information). Have this information ready when you set up your device.
If you are connecting your base station to an Ethernet network that already has an Internet connection, you may need an account name and password to access the network. Check with the network administrator if you’re not sure.