If you signed up as an educator, you already have a class! Good work. Click on "Studio" in the top navigation menu from anywhere on the site, and you'll be taken to the Educator dashboard which hosts your classes.
Don't see "Studio" at the top of the site when you login? Then you probably created a regular account. No problem. Create a class and transform your regular account into a class account.
Link to a step-by-step walkthrough and video on creating classes.