Tweening basically gives you the ability to make objects/shapes move without actually having to do it frame by frame. Flash can create two types of tweened animation. 

1. Motion Tweening: Here you define properties such as position, size, and rotation for a symbol, group, or  text block at one point in time, and then you change those properties at another point in time. 
     
2. Shape Tweening: Here you draw a shape at one point in time, and then you change that shape or draw another shape at another point in time. Flash then interpolates the values or shapes for the frames in between, creating the animation.

Tweened animation is an effective way to create movement and changes over time while minimizing file size as compared to frame-by-frame animation. This is helped by the fact that Flash stores the values for the changes in between frame.

Motion Tweening: 

Flash can tween position, size, rotation, and skew of instances, groups, and type. Additionally, Flash can also tween the color creating gradual color shifts or making an instance, group or type fade in or out. To tween the color of groups or type, make them into symbols. If you tween an object that is not a symbol, Flash automatically converts it to a symbol and names it tween1, tween2, tween3, and so on. When tweening position, you can make the object move along any non-linear path. 

Let us attempt to make the above .swf to obtain the object moving, rotating and scaling at the same time.

1. Open a new file in Flash ( Ctrl + N ). Select frame 1 on the timeline, draw a square on the Stage.
2. Press 'F6' to convert frame 10 into a keyframe. In Frame 10 move the circle a couple inches to the right. To tween the size of a group or symbol, turn on Tween Scaling. Now highlight frames 1-10 and choose Insert > Create Motion Tween. If you drew the object, Flash automatically converts it to a symbol and names it tween1 and tween2.
3. To see an instance of tweening in the size of a symbol, copy and paste the square in frame 20. Right-click on the symbol and chose the scale options. Using the handles which appear at the side increase/decrease the dimensions of the square. 
4. Now highlight frames 10-20 and choose Insert > Create Motion Tween. Here remember to check the 'Tween Scaling' and select the ' Clockwise ' option in the Rotate dropbox.
5. Press Ctrl + Enter (generates .swf file) and Voila !! you should have a tweened image  :).

To do a motion tween keep these in mind: 

• The objects you are tweening need to be grouped together or symbols. 
• They allow you to use automatic rotation, clockwise, or counterclockwise rotation.
• It allows you to scale the objects and move in certain directions.

Note: Do not attempt to make the buttons layer while tweening just try the tweening part of it.