Where can I find free information on how to become successful in real estate?

I am enrolling my son into a real estate business classes here in Boston. He just graduated and I want him to have work as soon as possible so that he will learn to be an independent man. A friend of mine who owns a real estate firm offered a job vacancy for my son. I want him to learn a few things before he enters the business. Where can I find free information on how to become successful in real estate? My son needs to know all the business things related to a real estate business.