Account
First, go to https://www.onshape.com/en/education/sign-up and create an Onshape account using your personal email to begin using it. To gain access to the team folder, email Mr. Reiber or tell him in person the email that you used to sign up.
Learn
Create a new document to practice. make sure not to create it in the team folder.
Open this link in a new tab: https://learn.onshape.com/learn/learning-path/onshape-fundamentals-cad.
You can skip Navigating Onshape and begin with Introduction to Sketching. Follow the tutorials to begin learning.