Textbox.text : formatting

I have to finish a project by tomorrow and i need urgent help!!

How do i do something like:
[AS]textbox.text=“Text 1; Text 2; Text 3; bla bla bla…”+“Text4”[/AS]
and text4 to be shown bold or italics like this:
B]Text4** or Text4 ;

I know it sounds kind of stupid but i don’t know how to do this…oh…and please, please tell me a web-site where i can put a cool forum on my web-site.