Before you start adding groups and registering students, make sure your students can receive system emails. Some schools set up blocks to protect students from unwanted emails. However they need to be able to receive emails for login info and password resets. Please ask them whitelist the site and email address. Directions are here.
After you add a group, return to your dashboard to add students. Click on Users on your dashboard to add students one at a time, or in bulk.
Adding a group takes a minute “under the hood”. Give it a minute or so and the page will notify you when the group has been created.