You can create Shape Tweened animations using Shape option from the Tween panel of the Properties inspector.
Open flash. Set the stage dimensions by clicking the edit button on the properties panel. This will open the document settings dialog box. Set the dimensions of the stage to 550 by 200 and choose a background color to your liking.
Draw a vector (circle) the drawing tool in Flash. Give the circle a fill color of you liking with no stroke.
Click the 30th frame in the Timeline and insert a Blank Key Frame. To insert a blank keyframe right click in the frame and select Insert a Keyframe.
Now draw another shape with any of the drawing tools without a stroke. Also change the color to add a more dramatic effect.
Now right-click on any frame in between these two Key Frames and select Shape option. You can also select the Shape Tween option on the the Properties inspector.
Save your work in swf format and test the Movie (Ctrl + Enter). If you need a refresher on how to save in swf click here.
Note: Only vectors can be Shape Tweened (Not for Symbols). Note both the Tweens have different colors along the Timeline as shown above.