This page will show you on how to locate a computer MAC address
 using Apple Macintosh OS X (10.3 or greater).
 
Locate a MAC with OS X
  1.   Go to Apple Menu > System Preference > Network.
  2.   Select “Built-in Ethernet” from the “Show” drop-down menu.
  3.   Click on the “Ethernet” tab if not already selected.
 
The Ethernet ID or MAC is the six pairs of numbers and letters.
System Preferences