Assigning Instructors
When you create a course, you automatically become the Instructor for that course. If you want someone else to be the Instructor for that course, you must assign them the role of Instructor.
Step-by-step Guide
Go to the course in question.
Go to Course Administration > Users > Enrolled Users.
Click on the "Enrol Users" button at the top or bottom of the screen.
Find the user(s) in question and click on the "Enrol" button next to their name
When you are finished, click on the "Enrol users" button to close the pop-up window.
Important Notes
If you do not find the user's name in the pop-up window in step #4 above, it's most likely 1 of 2 reasons:
The user does not have an administrator account in your system. You can create an account for the administrator by following these step-by-step instructions.
Its possible that the user is already an Instructor in the course. Look at the list of enrolled users to see if their name already appears.