Test it out on the right==>
Open a new file. Change the name of Layer 1 to text. Click on the Add Layer icon or alternatively you can click on Insert - Layer. This adds a new layer just above the first layer.
Add another layer to the movie. Name the top layer downward motion and the middle layer upward motion. You should now have three layers in your file named (from top to bottom) downward motion, upward motion and text.
Hightlight the first frame of text layer and using the text tool insert some text in the frame. Convert this text to a symbol (Select the text by clicking on it once, then select Insert>Convert to Symbol). Name this symbol mytext and make sure that the Behavior is set to Graphic. Align this symbol to the center of the page.Open the Symbol Library (Window - Library). You shall find the mytext symbol in the listing. Click on its name in the library to display a thumbnail view of the symbol.
The first frame of the text layer is a KeyFrame. Right click in Frame 18 and Insert>KeyFrame. This copies the text across the remainder of the 17 frames.
Hightlight the first frame of upward motion layer, and drag an instance of mytext symbol from the library onto the stage. Align this to the center of the page. In the same layer, add a new keyframe on frame 18 and shift the symbol slightly above the original location. We shall now modify this symbol instance. Click on Modify - Instance, choose Alpha from the Color Effect drop down menu and decrease the alpha value to 0%. Insert a motion tween between the first and last frames. (Right-clicking on any middle frame and selecting Insert Motion Tween from the menu will insert the motion tween).
Now place an instance of mytext symbol on the first frame of layer downward motion and center it on the stage. Insert a new keyframe on frame 18. Place this symbol slightly below the symbol in frame 1. Change the alpha value of this instance and decrease it to 0% through Modify - Instance - Color Effect - Alpha. Insert a motion tween between the first and the last frames.
With eveything done, your layers should look like: