Go to the specific exam website page you want to enroll in, ie for CDL prep return to the CDL page or search the website for the CDL exam page. Once on that page Scroll down to and click on long blue rectangle that says: Start your exam prep today. This will take you to the next page, click on ENROLL NOW. This will take you to the next page where you enroll, scroll down to Proceed to Checkout. Enter your payment details and check out for enrollment. Next an email will be sent to you with a confirmation link to go to the exam, click on that and start your exam.
OR
You can also access the exam once you are enrolled by returning to the exam page (making sure you are logged in) Then scrolling down and clicking on long grey rectangle that says Quizzes.