ECE exams are administered at Prometric testing centers. You can find the closest testing center by going to
http://www.prometric.com
Before you can take an ECE, you have to receive a voucher from Excelsior College for each exam you want to take. For instance, if you want to take World Population, you either call up Excelsior or register via their website, pay the full amount, and then you receive the voucher in the mail. You take this voucher to the Prometric center, and they'll administer the test to you. You repeat this process for every ECE.