In Airport Utility
  • Under the Airport icon choose the Wireless tab and set the Wireless mode to "Create a Wireless Network"
  • Under the Internet icon click on Internet Connection and for "Connection Sharing" chooose "Share a Public IP address".
  • Under the "DHCP" tab set the beginning and ending range of IP addresses to be assigned to devices connecting through the Airport Express

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein