cant move objects

i have done everything that the tutorial (the very first one which is called roll a ball) says i should do. and still i cant make the ball move. i think the problem is with the script but i cant find it. i have attached a link to the project. any help would be greatly appreciated.
https://www.dropbox.com/sh/gealdupm0y2tf38/AAD2scmy21o2AGNiJgQQkV5sa?dl=0

 

plz post the script you use