Click on the small icon to open the editor
Click on the green round thing to add this layer
Click on the sizing icon to open the resizer
Click on the "left" and "top" buttons
Click on the resize slider and move it a little to the right
Now click on the two center buttons
...and move the slider to make the green disc a little smaller
Click on the bullseye icon to add a frame layer
Resize it so it is just a little larger than the green disc
Click on the grid icon to open the guides layer
Click on the colorwheel icon to open the gradient and color controls
If you did everything right it should look like this.
That's it. Demo over. Now we need to write the real thing.