Motion Guides

You can create a motion tween along a path using a motion guide

• Create a new flash movie
• Add a circle and group it
• Tween it across the screen from frames 1 to 80
• Right click on the layer and select Add Motion Guide

             
You can draw a line using the pencil tool or other tools

• Draw a curved line on the screen

• Click on the circle

• If it has not already snapped to the line drag it until the registration point in the middle snaps onto the line
• Select the last frame
• Drag the circle until it also snaps to the line

• Test it

Orient to Path

• Start another movie
• Draw a triangle
• Group it
• Tween it across the screen
• Add a motion path
• Snap the triangle to the line in the first and last frames

Notice the triangle follows the path but it is very stiff

• In the property inspector click on orient to path

You may have to rotate the triangle at each keyframe so it aligns to the motion guide
  
Now it should follow the line and rotate with it