Show one screen, hide another?
Solution 1:
The following solution assumes that you are using a Mac running OS X Mavericks, and is connected to the same Wi-Fi network as your Apple TV.
You can use the Apple TV as a secondary display over AirPlay. Go to System Preferences → Displays, and select your Apple TV under AirPlay Display.
You can both mirror the contents of your Mac, or use Apple TV as a second display (your desired use case).
Go to Arrangements under Display preferences and uncheck Mirror Displays to use Apple TV as an extended display.
