1. Open the Apple menu at the top-left of your screen.
2. Click “System Preferences…”
3. Click Network in the System Preferences window.
4. Select AirPort and click the Network Name drop-down menu to select the wireless network you wish to connect to.
5. Enter the security key or passphrase of the network if prompted. If you want to connect to the network automatically the next time the network is in range, click “Remember this network”. Once you are finished, hit “OK.”
6. Click “Apply” and you should now be able to connect to the network.