TIP: Tired of going back and forth between your drawing and your animation page? I thought so. The keyboard shortcut Ctrl Tab toggles back and forth between pages.

Press the New Frame button to add frame 6.

Copy and paste the 3 group.

Press the Copy Frame button 3 times to make 3 copies.

Press the Previous Frame button until you return to frame 6.

Copy and paste the sections of the 4 over the 3 as shown. Press the Next Frame button to advance to the next frame. Etc.