Tweet?

I was told by a knowledgeable person that to sell books you have to really get involved in social networking, which includes "Tweeting". Now I'm a person of reasonable intelligence and I'm fairly savvy with today's technology. Somehow I missed the training manual for Tweeter. I received all these tweets that I don't understand and don't know how to respond to. I send out tweets that are not responded too, or at lease I don't know if anyone responded.
   I have several followers but I'm not sure what they are following and I'm following several tweeters although I'm not sure what I'm following. It is a different world and I always thought I was current until now. So, if anyone understands this tweet thing I would appreciate a short dissertation on how it works.

As of now book sales are moving along and I'm expanding my marketing base. Marketing is harder than writing. Writing you can put it down and when you work on it you can focus on just your ideas.