1. First you'll have to make a new document and insert a keyframe in the timeline. Draw a shape in that keyframe. (I drew a circle)
2. Now right click on that keyframe and select "Create Motion Tween". It will then convert that shape into a symbol.
3. Next insert a keyframe in the timeline where you want the tween to end (I put mine in frame 25) Now in that frame drag the shape your tweening in any direction. (I dragged mine from the left side of the screen to the right)
Here's an example of how your timeline should look:
4. Now you can press return and watch the circle move across the screen.
Final Result: Download Source File
