Use arrow keys to move You can use this script for yourself by pressing see inside and putting the script in your backpack. I have outlined what is a backdrop and what is a sprite, so make sure your floor is not part of the backdrop when you are making your game.
Essentially this is the movement script that I used for my game Dox's Adventure which you can find here: https://scratch.mit.edu/projects/293149815/ or by searching 'Dox's Adventure'