Create an animated button
1. Draw/write/import a picture whatever you want to be your button content.
2. Group everything as a button, or with one object convert it to a button, either way is fine.
3. In the Button panel, select the following:

4. Now in the outline this looks like this:

5. Up/Hit state: how it looks when you dont mouse over
Over state: how it looks when you put your mouse on the button
Down state: how it looks when you click the button (and hold it to view the effect better)
6. Change the Over state. Do this by altering the colors, text whatever. If you want to animate it, select all objects and group them as a sprite. Now you create a new timeline within you can make anything happen

7. Change the Down state to suit your needs as in 6. I wouldnt animate this one since it only is viewable for a fraction of a second, since nobody clicks and holds their mouse. If you animated the Over state I would make the down state look as the end state of the over state, so it gets a fluent effect.
8. Add an action to your button and you are done!