In order to enroll students they will need the enrollment key to gain access to your course shell, or you can also add them in yourself. The enrollment key can be obtained by going into the course shell settings under availability (Explained in the course shell setup page)
While the enrollment process depends for the most part on student action, there may be times when you will need to manage your own enrollment list. For example, when a student drops your course it is your job to manually delete them from the list, or you may want to add a colleague to your class as an observer or collaborator. You can accomplish these tasks from your Administration block.
To modify student enrollments, use the Assign Roles link.
In the next page you will see the students link.
Once you have clicked on the students link there will be two panels. The left panel contains currently enrolled students and the right panel is where the possible students are.
A) Search for the student you are looking to add
B) Highlight the students name
C) Click the left "Add" arrow to enroll them into the course
You may also add Instructors (Instructors may edit your course shell), Non-Editing Instructors, and Guests. Its the same process but instead of going into the student section in step 2, choose whichever role you want to give the user.