Trevor,
You need to login to the extranet (
extranet.extremenetworks.com) . If you don't have one, check
https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-create-an-extranet-account/
Once there select
Enter Training and Certification.
You then need to purchase an Exam Voucher, if you don't have one. Select
Purchase Exam Voucher.
This option will take you to a page where you will have to select the Exam, payment method and complete Billing Information.
You will then receive an email with the exam code. Something like this:
You can then select
Take an Exam.
where you will be asked to enter the exam code that you received in the email.