Courses in CS department belong to "A" or "B". Insert "C" for course outside CS department and undergraduate CS courses.
Choose department (if not CS)
Click confirm then click an empty slot to pick your new course.
How to pick a course?
1) Move your mouse to a course in the graph.
2) Click to choose this course.
3) Move your mouse to the box in the course schedule.
4) Click the box to confirm your pick.