You start out with a new page as always, then draw a shape (ex. a circle). You select it with the selection tool (black mouse) and convert it to a symbol. You then right click on the layer with the ball and select “add motion guide”.
That layer will put the circle into the motion guide group (it will look indented under the motion guide layer). Then, on the motion guide you use the paint or pencil tool to draw a line that goes in the way you want your shape to go. Basically, the guide line for the movement of the circle. Once that’s done, set the motion guide to go for as long as you want it (set a keyframe there).
Go to the first frame and the layer the circle is in and move the circle to the beginning of the motion guide’s line. Then create a keyframe on the circle’s layer and put the circle where you want it on the line to be when it’s done .
If you make the keyframe where the motion guide ends, put the circle on the end of your line. If you want to vary the speeds, play with the keyframe setting and set them to different places and lengths.
Then, create a motion tween on the circle’s layer and test it out. Done!