Hello there, MaryFromDowney.
The following Knowledge Base article offers up some great information on AirPlay functionality:
About AirPlay Mirroring in OS X
http://support.apple.com/kb/ht5404
If the MacBook model is newer than the one mentioned in your information above, then this section should prove helpful:
If you don't see mirroring options
If your Mac and Apple TV are on the same network, but no AirPlay Mirroring menu appears, your Apple TV may be asleep. Simply press a button on your Apple TV remote to wake it up. After a few seconds, the AirPlay Mirroring menu extra appears. If you still don't see the options you expect, make sure your Apple TV has the currentsoftware update installed. Also make sure that you have the "Show mirroring options in the menu bar when available" option selected in the Displays pane of System Preferences.
Thanks for reaching out to Apple Support Communities.
Cheers,
Pedro.