Creation of Motion/Shape tween using timeline is the basics of Flash.

A shape tween is tweening a vector images' transformation from one configuration to another. During a tween, the computer generates all of the frames of animation required to transform vector shape from one shape to another.

To implement a Shape Tween, two keyframes must exist with a vector image on a single layer no symbols can exist on the stage with it. The shape should be in one configuration in one keyframe (say, triangular and blue), and in another configuration on the second (a red circle for instance). Select all of the frames between the two keyframes you wish to tween, right click, and select create shape tween. The frames will be replaced by an arrow. To test, move the playhead to the first keyframe on the left and hit enter. The shape should mold itself to the new configuration.

Shape Tweens can only be done on vector shapes like those drawn with the tools on the toolbar. Shape Tweens can scale, translate, transform, and change color, though it may not do so in a way that you expect so be sure to test the animation to make sure it works as you like it. In order to animate a symbol, a Motion Tween is needed.