MACROMEDIA FLASH 8-FLASH Tutorials Manual page 55

You can create several kinds of animation in an FLA file, such as
motion tweens, shape tweens, and frame-by-frame animation. In this
tutorial, you will create a motion tween. A motion tween is an
animation where you define properties such as position, size, and
rotation for an instance at one point in time, and then you change
those properties at another point in time. In this animation, you
change the brightness and size of the instance.
12. Select any frame between Frames 1 and 15, and then select Motion from
the Tween pop-up menu in the Property inspector.
The span of frames changes color and an arrow appears between
Frames 1 and 15 (see the following figure). Notice how the options in
the Property inspector are different when you select a frame compared
to when you select a movie clip instance.
Create a motion tween between Frames 1 and 15 on the movie
clip's timeline.
You can also right-click (Windows) or option-click (Macintosh) the frame
and select Create Motion Tween from the context menu instead.
13.
Select any frame between Frames 15 and 30, and then select Motion
from the Tween pop-up menu in the Property inspector to create a
second animation.
14.
Click the playhead and drag it across the movie clip's timeline to test (or
scrub) the animation.
Adding animation to a timeline 55