Without students you cannot schedule sessions, so you can start adding students by simple steps as given below.
1. Navigate to Users in header menu
2. Click Add User button that is found on the right side
3. Mention Full Name and email address of the student
4. Choose the Role as Student
5. Click Add
An auto-generated password will be sent to the added email address, using which the students can login.
You can although schedule sessions by just using this email address