It's actually quite easy, A lot of it is common sense and a lot of it has to do with the laws and ethics of selling a vehicle. Also covers advertising, what to do and what not to do...
The book is lengthy but it's an easy read and a lot of it is pretty straight forward!
I do believe that you have to be sponsored by a dealership in order to get the license, call OMVIC and double check.
Good luck!
*edit - Forgot to add that in order for you to be registered with OMVIC you must show your Georgian College certificate, which means that you have to register with GC anyways, so getting the book for someone else would be useless because either way you'll get it when you register with GC.