When logged into your account, navigate to the menu in the top left of the page and select Courses from the list of options.
You can view the entire list of Dr Frost courses using the link at the bottom of the page.
From here, you can use the search and filters to find the course that is most relevant to you.
Once you've viewed a course, it will show up under the recently viewed section on your courses page so you can easily navigate back to it when you want to resume working on it.