First way.. create new document..
Create a rectangle using rectangle marquee tool. Click Select>inverse and then fill the selection part with black . Click Edit > fill > black
Now .. create a little circle with elliptical marquee tool. ( press shift button to make the perfect circle )
Fill the circle with gradient tool .. Gradient color black to white or as you want.
Now we will make the ball move..
Click window > animation, to appear animation bar ( animation window )
Click Duplicate selected frame to create a new frame
Move the ball on frame 2 to center of the left side
Then … Click tween animation frame to make ball move smoothly.. if you want the ball move more smooth just make a lot of frame.. but for example I use 5 frame only.
Here is the result… Click play button to try
With same way ..
Create new frame with duplicate selected frame ( last frame) , then move the ball to center of the bottom, then create tween animation frame..
Create animation from center bottom to center right..
and the last move..
Click play button..
If the moving of the ball is okay.. then save to gif
click File > Save For Web and Devices
and the result is
Have a nice day..