A guide layer is a layer that's invisible
in the final, published Flash animation.
You can place a path on a guide
layer to control the motion of an object
during animation.
       Start by creating a new document in flash.
       First of all, we will make the object which we need to move.
       I am making a simple circle.
       The object needs to be a movie Clip otherwise it would not work with the guide
        layer.
       Now make a new layer and draw a line on it, this line is the path that the ball will
        follow.
       I have drawn a wavy line with a green color.
       The color is not important here because it would not be visible in the output.
       Now right click on the layer with the path and select the guide option from the
        context menu.
       This will transform the layer into a guide layer.
       You will know that it has successfully transformed when you see the icon of the
        layer change.
       But the ball is not bound to the guide yet, to do that drag the ball layer with your
        mouse and move place it on the lower side of the guide layer.
       When the ball layer becomes a part of the guide you will see it like the image
        below.
       To make the ball move with the line, the ball needs to be on the line first, drag the
        ball on the line such the circle showing the center of the ball is on the line.
       Now press F6 on any other frame in the ball layer to insert a new frame there.
       Press F5 on the same frame in the guide layer to extend the guide layer upto that
        frame.
       Now in this frame change the position of the ball but you have to make sure that
        the center of the ball is still touching the line.
 At last right click on the middle of ball layer and choose classic tween to tween
  the ball. Press Ctrl+ENTER to test the movie and you will see the ball move
  along the line of the guide layer.