1) Open the Google Sheets document you want to set up notifications in.
2) You can choose to be notified when changes are made, or when a user submits a form. You can also choose how often you should be notified. A daily notification for the days changes, or an immediate notification following every change.
SOURCE MATERIAL:
https://support.google.com/docs/answer/91588?hl=en
VIDEO TUTORIAL:
https://www.youtube.com/watch?v=6jxEV4xCc2I&list=UUdgTksw283OFC78pFcwXIdA