Just walk with A and D or with < and >. You can also jump.
I am aware that the footsteps don't always play and sometimes when you are walking it says walking = false. This happens when you change directions too fast. I made this in like 15 minutes so go easy on me. If you come across any other bugs feel free to tell me. This was my first attempt at animation in my games, I usually just change from one costume to another, but this time you change costumes continuously as you walk to make it look like you are taking steps instead of hovering.