You need to sign in to AWS.training to register for an AWS Certificate exam. Then, click 'Certification' in the top navigation. Next, you have to click the AWS Certification Account button, followed by the Schedule New Exam. Then, find the exam you want to take and click on schedule at PSI or Schedule at Pearson VUE button. You will be redirected to the test delivery provider's scheduling page, where you can complete your exam registration.