Hey Catherine,
I took a look at your account but I don't see any record of you registering a book on our website. If you have not yet registered your book, please do so using the following link:
http://www.manhattangmat.com/access.cfm. Alternatively, you can follow the instructions on page 7 of our Strategy Guides.
Once you have registered your Strategy Guide, you will have access to the CATs in the Student Center. After you log in, simply click on the CAT Exams & Diagnostics tab.
I hope this helps. Please let me know if you need further assistance.
Best,
Matt Mapplebeck
Student Services Associate
Manhattan GMAT