Q. How do I setup my Mac for Dual Display?

How do I setup my Mac for Dual Display?

Start without having the VGA cable inserted into your Mac.

Open System Preferences.
Under View choose Displays.
Click the Arrangement tab.
Enable (check) "Mirror Displays" in the bottom-left corner.
Set the screen resolution for the LCD (the Mac's built-in Display) first.

Then plug in the VGA adapter that goes to the monitor and click on Detect Displays.

Now set the screen resolution for the monitor.

Exit back to the Mac desktop. You are done!