1. Import an image of a waterfall into Flash.
2. Set this picture as your background, name it, and lock the layer.
3. Create a new layer, and name it "waterfall".
4. Next, create a small circle with a gradient fill. Convert this to a graphic object, and name it "drop".
5. Convert your "drop" graphic object to a movie clip, and name it "dropmov".
6. In the "dropmov" time line create three key frames. Insert the following action into the first key frame:
pos = _y;
7. In the second key frame, insert this action:
_y = _y+2;
if (_y >300)
_y = pos;
8. Then, in the third key frame, insert:
9. Now, return to the main time line, and reduce the alpha of the "dropmov" movieclip to 30%. Duplicate the "dropmov" movieclip such that it covers the whole water fall.
Run the movie and you should see the above effect. Well done!