How do I post something on someone else's profile, on Twitter?

[smalltrip561]

I know about the @username and everything but what im confused about is.. When im looking at someone page on twitter and there is that box that says "tweet to @username", do i post my message through that, OR do i start the message on my own page starting with the @username. I thought i had to tweet it through their profile, like on facebook, for them to get the message, but they didnt reply. I don't know whether this was because they didn't recieve it or just they didnt wasnt to reply.

Another thing
How does one person know whether someone has @usernamed THEM.. Like, there's no notifications like facebook and from what i know ( VERY KNEW ) the post doesn't show up on their profile.. so yeah how does someone know?

SORRY FOR BLABBING

[zeric7x]

You cant. You can tweet responses at there @name or retweet there tweets but thats it. I do not believe you can send direct messages with twitter.