Minecraft 1.8.1 mods for the uninitiated

I have no gaming experience other than watching my 7yo play minecraft and bitch at me that he wants to download some orespawn or swords mod and I cannot get that done for him Help an old grandpa out and tell me what I need to do to load these things so he can play Yesterday I loaded something called Crazycraft watched it load for 10 minutes and can't find out how to execute the thing

This is for Gamespot related issues.