I'm not sure exactly what you are asking but i'll try and answer it.
Create two layers.
On layer one to the top, use the text tool to write some text.
On layer two draw a box (with a border if you want) with a fill colour perhaps or even nothing at all! (so long as you have a border). If you want a semi transparent look, convert the box you drew to a Movie Clip symbol and alter its 'alpha' settings.
yeah that works now another question how do i make it scroll
Well, i'm no expert but i'm pretty sure you name the text box e.g text1. Drag a scroll bar from the UI components panel into the text box and it should snap to fit. Make sure that the scroll bar is linked to the text box with the right name, e.g text1.