Step 1. Enable course editing
In order to make changes, you should activate the editing mode (if it is disabled) by clicking the gear icon and then turn editing on.
Step 2. Adding a section
At the end of the current sections on the course page you can find the Add topics button. Click it.
You will see a dialogue box which asks you how many sections to add. The new topics will be automatically added to the end of the current materials.