How do I build a movie clip in Actionscript 3

How do I build a movie clip in Actionscript 3

How do I create the AS3 equivalent of a moviescript with multiple frames?
If I were using the Flash IDE, I would put whatever stuff I wanted on
frame 1, other stuff on frame 2, etc. and step through the frames as the
user clicks the "Next" button. Or perhaps put in keyframes and tweens and
let the system play through the frames at a fixed rate.
I don't see a way to do this in AS3, even though all the descriptions I've
seen say that Flash CS3 turns your timeline and frames into ActionScript,
and I would like to know how to do the same without having the Flash IDE
(e.g., working in Flex).
Let's take a simple example: I have 3 frames. Frame 1 contains the splash
page (a lot of text and a button). Frame 2 contains one image, one label,
and one button that says "Next". Frame 3 contains two images and one
label.
How would you build that in AS3?