Guide Layers
Exercise 2: (You may use text, shapes or saved images for this exercise)
Open a new File. 
Create another simple shape, with any fill you choose. Select it and make it into a Symbol (F8). Make sure its the size of a nickel or dime and is on the far right or left hand side of the Stage.
Add a 'Guide Layer'
. With the guide layer highlighted use the pencil tool (with the Smooth option selected), and starting from the middle of the circle/shape make a wiggly sort-of line, make sure that the lines do not intersect.
In both the Guide layer and the first Layer select frame 20 and press F5 (adds blank frames).
Select keyframe 1 in your Layer, insert a Motion Tween.
Select frame 20 in your Layer and insert a keyframe. Within the same keyframe highlighted drag your circle to the end of your line.
This should have created a motion tween using guide layers. Guide Layers basically just aid in where the motion of your image goes. It "guides" the motion of the object.
When you publish your file ([File] -> [Publish]), the guide layers do not show up, they become hidden. Publishing shows you what you've done so far, outside of the Flash program, using the Flash Player. To view the published file, just find where you've saved your file to and it should be there under the same name. It will be a .SWF file and the icon looks like this: 
To see what the example should look like go here Guide Layers