How Do I Setup A Guest Network With The AirPort Extreme?
Open the AirPort Utility on your Mac from inside Applications > Utilities. Select your network and click the Edit button. Find the Wireless tab and select it. Look for the checkbox named "Enable Guest Network". Check the box to enable your guest network and then add a name and login credentials. Click Update when finished. The AirPort Extreme will reboot and once it's finishing you should see a new guest network listed alongside the other available wireless networks.