I really think you need to add some much better and clearer instructions on how to set this all up. As a parent who has not installed or played with modding of Minecraft (and know almost nothing of the game itself), there are a large number of assumptions made. Take this statement "You also want to download forge and extract the resulting folder to your desktop. This will make things easier. files.minecraftforge.net" - it has taken hours and a heap of googling to get the right files, in the right place, "extracting" them correctly etc etc. Now we are getting errors loading the first Mod and I have to go back and do this all again with 1.7.10 instead of 1.7.2.
Please update this first post (or new thread) with a complete "from nothing" how to setup/all prerequisites so that the course works - one for PC, one for Mac, separately.
Honestly, I think that'd help a LOT.