We are in Day 4 of Twitter practice in our Blog Book Tours class. A few folks are getting themselves very confused. That's not uncommon, and the only suggestion I have is to keep plugging away, and eventually you will "get it" by rote. Post and read three times a day as described in previous lessons. Get a sense of the interaction for a few days and it will sink in. Twitter is deceptively simple, and this sometimes adds to the confusion. Don't make it more complicated than it really is.
One important point. When you go to Twitter, make sure you are signed in. You should get a sign-up window if you are not. Obviously, until you are signed into your account with your password, you cannot read your timeline, which means all the updates of the people you are following and your own posts.
And start reading http://www.twitip.com on a regular basis. Think of it as Twitter Berlitz. The more you immerse yourself in this foreign language, the more quickly you will understand what everyone is talking about.