Here's the basic introduction - https://www.youtube.com/watch?v=QK7ZndwzOJY
How to use the Google Classroom Share Button - https://www.youtube.com/watch?v=D9rgs3jLwr0
Using the Student Share Extension - https://www.youtube.com/watch?v=ynjLWjrDwko
Using the Teacher Share Extension - https://www.youtube.com/watch?v=LYuBn9xgSh4