Purchase a Sage GoReact slimpack as a standalone product or bundled with a Sage text. Then you will register via a course link provided by your instructor. Note: Without the slimpack and the course link, you will be unable to register.
Click the link you receive from your instructor, and you'll see a page like this:

Enter your information, and you will be guided to a page on which you enter your access code. To enter your code, click the “Enter Access Code” button and type in the code where indicated.

On your dashboard you’ll find activities your instructor has assigned. Note that you will not be able to record video until your instructor creates an activity.