First you have to add the item to the list you've just created. See my picture.
However, your approach will result in a new list with only one item each time you click the button invoking this microflow. Because each time you will create a new list. So it is important to store the list somewhere so that you can later retrieve it and do add/remove operations on the list.
Ok, I see. So would it be better if I just had the mircoflow for add on the course to create the list and add to the list:
And then configure a save button at the end of the course listing page to trigger a microflow to show this list with all the selected courses in a new Fall Schedule page like: