You will need to sign in to the OCourse with the same method you used to register for the course (either through your account or Facebook). If you forgot how you registered for the course, you can always look at your OCourse Welcome email that will have either the username and email associated with your account or a reminder that you registered through Facebook and the email associated with your account. If you forgot your account password, simply click the "Forgot Password" link on the sign in page to reset your password.