Add a Keyframe
Flash CS3 Tutorial
How to Add Keyframe in Flash
Keyframes are used to define an object at a specific point in time.
For instance, you could set a keyframe at frame one where your object is transparent. A second keyframe is added at frame ten where the object is opaque. A tween is then applied between the keyframes and the object fades from transparent to opaque in ten frames.
Add a rectangular object to the workspace with the Rectangle tool (r key).
With the rectangle selected, convert the object to a movie symbol by pressing F8 (Modify > Convert to Symbol). Name the symbol in the dialog box.
The layer with the rectangle has one keyframe by default at frame one.
Click frame 10 and press F6 (Insert > Timeline > Keyframe). A new keyframe is added that contains the same content as frame one.
Click the first keyframe, then click the rectangle to access its options.
In the Properties panel, choose Alpha from the Color pull down menu. Set the Alpha value to 0.
Click between the frames (i.e., frame 5) and choose Insert > Timeline > Create Motion Tween. You can also right-click (Mac-Ctrl-click) the middle frame area and choose Create Motion Tween from the menu.
Test your movie (Control > Test Movie) (Cmd/Return (PC-Ctrl/Enter) to view the animation.