i need help with twitter.com so how do i send tweets to people ?

[Taylor]

[Computers]

Tweet something and hashtag them

If you want to tweet to Eminem do, Hey #Eminem, nice music you got

[JessicaT]

You have max 140 characters allowed... you have reply to a Tweet, RT or on top left there is a empty text box to enter a new tweet.
You can always use # tags with import words or a trend that your tweet is for.
If you want to refer to fellow twitter you can use @ symbol with the profilename or id.