1) Ask your teacher for the join class link and class password.
They can be found on your teacher's Edit Class page.
2) After you go to the join class link and enter the class password, you'll be asked:
If you click No, you'll be asked to create an account.
If you click Yes, you'll be asked to login.
Then your account will be linked with your class and your teacher will be able to see your books.
3) Going forward, log into your account by clicking Login at the top and logging in.
Don't go back to the join class link.