how to give use interface for creating body of mail

Dear All,

   I am using C# , asp.net 2.0 and Ajax1.0.

My requirement is that I have to I have to give user interface where

He write the body of mail and attach the file which has to tranfer through mail.

My question is how can I provides or which control should I use so that whatever user writes in same manner It will deliver that is if he has used new line or break. In body of mail should also show the same..

In short I want to build message textbox just like when we write new post message text box comes.

Please guide me.

Thank you