Sign into your account by clicking on the Sign in button located in the top-right corner of the page. After signing in, click on the Find Course Now! link to the right of your dashboard. You'll then be taken to this search page where you can find courses to enroll in.
If you are interested in a course, click on the title to view more information about the course. To enroll, select the large blue Enroll in [Course Title] button under the course title.