So far we've just been covering simple animation to tell a story; it required no input from the viewer other than to watch and listen. Now we're going to add user interactivity to our animation, by giving the viewer options to choose from that determine what happens next.
To start with, you'll need to extend your animation by one frame. I prefer to do this by copying and pasting my last keyframe on each layer, just to ensure that anything that I do on this last frame doesn't affect any tweens or other actions that I've already completed. Now, on a new layer, on your last frame only, just set up a simple option; depending on the story of your current animation, it can be a yes/no question, or any other option, as long as it leads to a result of two or more different animations depending on the choice (for the following lessons). Mine's a little cheesy--Lex has two lucky shirts that he wears for races, and wants to know which one he should wear, the blue or the green. I just created a text box with the question displayed on one layer, and then on another layer used overlapping rectangles and fills to make a simple button with the option "Blue" on it. Only make one button; we don't need to make all of them from scratch.