Once you have marked a Class as Private (in order to remove it from public Search), the Class becomes "invite-only". Students can only join if they are specifically invited via email.
To invite students to a Private Class, click "Share Class" on the Class screen (or in the Class's "Learners" tab in the mobile app), and choose the Email option.
You can invite dozens of users at a time, by separating their email address with commas.
Please note that students joining a Private Class will all need a Brainscape Pro account in order to access your flashcards. If you do not wish them to have to pay individually, you can contact us to discuss a class or company license.