As an administrator, you might want to enrol a new student in a class to get them going.
Start from Class Admin and search for the teacher or class you want to enrol your student in
Click on the title of the class: e.g. English B1 and you'll see this screen
And you're done.
Students can also enrol themselves in upcoming classes via the Live Classes dashboard. Only if there are enough spots available and they have credits for them.