You can search through our many courses in the edX course catalog. When you see a course that looks interesting click the course card to open the course about page. There you'll se information about the course contents, the start date and more information. To register for the course, click the green box that says "Enroll Now".
This will lead you through registering on edx.org if you haven't done so already. Once completed the course will be listed on your dashboard.
The start date for the course will appear in the upper right. Please note that while you will be able to see the course on your dashboard before it starts, you will not be able to open the course or access materials until the course start date passes. If the course has started you will see a blue 'View Course' button. Click this to enter the course and begin.