post 1 on twitter

before this class, i tried to have a twitter page. my sister and best friend both have them and use them frequently. after i tried to use it for a few days, i decided to delete it. I did not understand how to make it work or what it was supposed to do. to be honest, i still dont understand how to use it! i am supposed to post and talk to people of it and i have no idea how!! i do not understand the "@ user name" to comment to someone but it stays on your page instead of the other persons? I really do not understand how to use it!