Click the green flag. Change 'speed' from 1 to higher values to change the frame rate.
Movies, games, programs in general work similarly to how a flip-book works. They flip through snapshots of something from one moment to the next and they do it so quickly that it looks to us like there's a single moving image. They create the illusion of movement by re-drawing the same image - slightly changed - at different places in different "frames"/pages. This is kind of how Scratch works. You draw one snapshot. Then you either draw other snapshots separately or you tell the images in the 'scene' where to go and how to move as you flip through the book.
