oh and when you get there go to the mods folder and also if you don't have forge go onto minecraftforge.com download the appropriate forge double clime it then it should get put into versions folder it will also say complete

The Main Mod That You Have To Have Other wise the cages will be gone is the fossils and archeology mod for 1.7.10 and build 7.3.2 and the llibrary and if you don't know how to install mods or maps its easy just go to ~/Library/Application Support/minecraft in finder paste this in in the search bar which you can get to by pressing shift+command+G