As a teacher you are able to view all CodeHS courses from your teacher account. To view a course as a student click on student in the upper left corner.
From there you will see a list of courses you are enrolled in. To enroll yourself in an additional course click on My Course at the top of the page. You will see a section titled Courses I'm Teaching and another section titled Courses I'm Enrolled In.
Under Courses I'm Enrolled In click on view course catalog to enroll in additional courses. Search for the course you want to enroll in and click on Enroll. If you are already enrolled in the course you can click on View.