There are many ways to animate objects. All you need to do for action to occur is create a couple of frames, create an object (or objects) in the first frame, and then change them in subsequent frames. You can move the object, rotate it, resize it, skew it, or change its opacity, just to name a few possibilities. Changing an object in consecutive frames is how cartoon animators go about their work — to have the Road Runner outfox Wile E. Coyote for a few seconds requires hundreds of frames of hand-drawn artwork.

In Fireworks you can go the route of the cartoon animator and create a change in every frame, or you can let Fireworks automate the process for you by tweening symbols. In animation tweening is when you create two instances (copies) of a symbol and then change one instance to make it appear different. When you apply the Tween Instances command to the instances, Fireworks fills in the blanks and creates action that you can distribute over a number of frames.

You can use tweening only on symbol instances. Tweening does not work on your garden-variety objects that you create with drawing tools and don't convert to symbols.