A

You need to a course before you can start to add content to it. Students do not have this panel showing - they are enrolled when you link their class to the course - see here for details.

B

From PIM click the drop-down button at the side of the window.

C

Highlight your new Course and click (twice - the first click just closes the long drop-down panel) to move the Course to your My Courses list.

D

Students are normally enrolled onto courses by you linking their class to your course. Their ability to enrol on other courses is switched OFF by default - they do not see the Course Catalogue panel that you do as teacher. You can Unsubscribe from a Course