Hi Marie,
Adobe Certification is achieved by sitting and passing a single exam in the product that you choose. The exams consist of approximately 70 multiple choice questions and are taken in a closed book environment, just you and the questions with no access to the software.
Here's a link to the Adobe Certification page where you can find out more:
http://www.adobe.com/support/certification/
And here's a link to the exam prep guides that outline the study critera including some practice questions:
http://www.adobe.com/support/certification/exams/
I hope that helps
Paul
