TO CONNECT THE APPLE TV,
if you are refering to the connection between Mac Book pro and Apple TV,
one the must important thing, is you need to be connected to the same internet conection for example same connection that your Mac Book pro is connected to Modam you have to connect with the same passward to same Modam.
then open the Itune in your Mac Book pro, then select the option Adanced from top bar baner in your secrean then choos Trun ON the Home Sharing ( you be signed in to your Itune account though first in your Mac Book pro )
let me know when try the above,