Creating elements for an animation is the same as creating objects for any other graphic. You can also import graphics to use in an animation.
Once you have created or imported the graphics for your animation, consider making symbols out of the objects that you intend to use in more than one frame.
If you place two or more instances of a symbol on a frame, and change the look or position of one of them, you can use tweening to automatically draw intermediate instances and distribute them across multiple frames.