How do I share my Internet connection with another MacBook via WLAN?
If you are using your WiFi to connect to the internet, you cannot use it to also create a local network for other computers. If you are networked via something not-Wifi (Ethernet, FireWire, USB, etc.) then you can share your connection via WiFi.




Go to System Prefs > Sharing.
Select your existing connection under Share your connection from:
Select Airport under To computers using:
Turn on Internet Sharing with the checkbox on the left.
The network name will be the name of your computer.