How do I ask somebody a question or make a comment on somebody's twitter page?

[V for Vendetta]

1. What does "RT" mean before somebody's comment
2. What does "@name" mean in a comment and how come sometimes it says "@name" in the middle of the comment and sometimes at the begining
3. How do I tell which comments are from the person whose page I'm on and which ones are another person's comment
4. How do I respond to a specific comment in the list?

[Courtney Bieber]

1. RT means to 're-tweet' somebody's comment, so all of your friends can see it too.
2. @'name' is just tagging somebody in a comment and if @'name' is at the start it means that the comment was directed towards that one person.
3.if your on your friends profile, only there comments [tweets] will be on there page.
4. if you want to respond to something that someone has said move your mouse over there comment and in the bottom right hand corner theirs a small 'reply' button click on it and just start typing what you want to say then press update.
i hope i helped =D