Hello,
When you click Create Tutorial, the Anatomy of a Tutorial page contains the information you need to get started: How to create a tutorial (video), How to create a video with Screencast (video), and Guided Tutorial Tips (Help page).
The only thing that I would caution you about is the share. If you choose Share in public gallery, it is live in the gallery for everyone in the world to see as soon as it finishes processing. If you only want your class to see it, then choose Share with specific individuals and then enter their email address or A360 sign in ID.
If you want to examine the nuts and bolts of a finished tutorial, you can Duplicate a tutorial to get author/edit permission. You can then edit and modify the tutorial as much as you want. Please don't duplicate an existing tutorial and then share an exact copy in the public gallery.
Hope that gets you going.
Cheers,
Paul

Paul Normand
Principal Content Developer/SME
Design Lifecycle and Simulation (DLS)
Autodesk, Inc.