Grab the spinner (the gray and yellow thing) and spin it with your mouse. Let go, and it will spin for a while before stopping. Don't hold the spinner for too long, else it won't spin. It's supposed to spin by itself for a second or two, else you're doing it wrong, but you can just press the "Spin" button. Don't spam the button. Just click it once. The color of the spinner can be changed with the "Color" slider on the top.
Just a quick project to pass some time :P Art by me, except the button from the Scratch library.