Click the Bearstack:

Tip: If you only see a cat, you can download the bears project from scratch.mit.edu/bearstack
Drag a move block into the Scripts area.


Click the Events category. Drag out a when this key pressed block and snap it on top:

Try pressing the space key on your keyboard.
You can use the pull-down menu to select a different key (such as 'right arrow'):

Now press that key to move.
Next, choose a starting point