Apple TV FAQ
How do I connect to my Apple TV?
First, go to your settings then to DISPLAYS. Turn Airplay on. On your top toolbar you will see the rectangle with the arrow at the bottom. This is your Airplay icon. Click on this. Find your room number in the drop down. This will prompt a display of a 4 digit code on the AppleTV screen (displayed on projector). Put the code in the box displayed on your MacBook.
If your Airplay icon is not displayed , click on system preferences> displays. Make sure it says yes after AirPlay Display.