Turning on Mirroring (Connecting laptop to projector)

Sometimes when you plug your laptop into your projector, nothing shows up.  The reason for this is your mirroring is turned off.  To turn on your mirroring, here are some simple steps to follow:

Once the Mac and projector are connected, click on the Apple Menu in the top left corner of your screen.

Select System Preferences from the drop-down menu.

Select the Displays icon.

When the Displays window appears, click the Detect Displays button.

At this point your Mac and projector should be synchronized. If not, try following the steps below:

• Click on the Apple Menu in the top left corner of your screen. 
• Select System Preferences from the drop-down menu. 
• Select the Displays icon. 
• When the Displays window appears, select the Arrangement tab within the menu bar.
• Check the Mirror Displays box in the lower left-hand corner of the window. (Note: After checking this box, please wait several seconds. Once the displays are mirrored, you should see the same image on both your projector and computer.)

See one of the tech interns if you still need assistance!

Source: http://www.meetingtomorrow.com/cms-category/how-to-connect-a-mac-to-a-projector