Twitter ettiquette...what's the deal?

[Daisyhill]

I joined Twitter a week ago...I have a few followers who I don;t know but who's profiles show that they have the same interests as me so I assume they've found me through searching...now..I notice that people have conversations through their tweets...is it the done thing to just direct message a follower to comment on one of their tweets? Or not? Is there another way of commenting on their tweets? I notice that some tweets appear on other users pages that look like part of conversations...but how do you know who'se talking to who???
ok...but how do I comment myself?

[MisunderstoodOverlord565]

It will say @whoever...which is their reply to that person if you click that profile name it will take you to the q that was asked. If that makes any sense.