To create a new course, you must first complete the New Instructor Orientation. Once you've completed it, you should find the Create Course button on the dashboard.wikiedu.org home page.
If the Create Course button does not appear for you (and you are logged in), it means you need to update your registration to let the Dashboard know you are an instructor. To do so, visit dashboard.wikiedu.org/onboarding and choose Instructor. (This is typically required if your first time using the Dashboard was as a course participant, or if someone else set up your first course for you.)