Adding to text boxes

[Mazarot]

Hey I was wondering how to go about adding things to a message box, like the one im typing into now.
Im basicly wondering how you can do stuff like the smileys along the side of this message so you click on them and it gets added to the text area...

[Nevermore]

You just grab the previous contents of the field, add the stuff on to the end, and then set the contents of the field as that. For an example, go to http://www32.brinkster.com/jjscripts/forfree/Smileys.html. The little picture is then added by the server when you submit the form.