Well, I think you may be missing the blueprints for the field. I showed our Field-Building mentor your question, and he thought you didn't have the blueprints. They are found here, under Arena Layout and Markings_RevA. The blueprints are on page 5.
http://www.usfirst.org/roboticsprograms/frc/content.aspx?id=18763
Hopefully this helps you guys out building your field!