Formating text in textbox

I'm trying to find a way to format the text in a textbox like changing fonts and colors and using images (or at least links to images) in a multi-line textbox. Basically what I want is to have some buttons that stay on the top of the screen and then have the user scroll down in the box to read all the information thats written but I want to be able to format the text and use italics and bold and things like that. I'm sure its simple but I can't figure it out for the life of me.