ATTACHMENT PROCEDURE..

Hi!
I have a web client, (for reference, Remedy WEB Client).
All I want to do is just add an attachment to the application.
could somebody help me out with this..

As some other information could you also tell me how the attachments are attached, so that it goes to the respective user.. I’d like to know the process which involves the transfer of attachment..
(This is not relating to any particular application, but on a general scale, like for example any of the email engines, how do they attach and send mails..?)

This is pretty essential guys, please help
John Bosco