I think if you ran yourself the links to Andrew Kramers Basic Training and maybe a little of Andrew Devis' tutorials on shape layers, you'd be able to create a Chat Window Simulation really quick.
After watching those tutorials if you have any specific questions-come back and ask.
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.