How to Connect Two Monitors in Mac OS X

Connecting two monitors to your computer can allow you to view and work on several different applications or programs at the same time.

Examine your computer to locate an available DVI, VGA, or HDMI video port.
Plug in the matching cable from the second monitor into the available port.
Wait for your computer to automatically detect the second monitor.
Click Apple menu.
Select System Preferences.
In System Preferences, click Displays.
Then click Arrangement.
You can place a checkmark next to Mirror displays, if you want both monitors to display identical data.