1. Open a new flash file and import image to the center of the stage in layer 1.
2. Create layer 2 above layer 1.
3. Convert layer2 to mask layer.
4. Draw a circle on mask layer 2.
5. Add 10 frames to both the layers and convert it into motion tween.
6. Increase the size of circle after twinning at 10th frame.
7. Lock both the layers and play the animation (timeline) and to see masking with animation.
