If your a DO med student you have to get authorization.
https://apps.nbme.org/ciw2/prod/jsp/login.jsp
For DOs, go to above site. Register, giving them your info. They email you back in about 1 business day with a ID # and password.
Log in with new ID number and provided passoword. Click the link Apply for USMLE go through the motions paying for the test, $560.
After test is paid for go back to above site and click on Review/Print Application.Click the reference ID number to view your application. At the bottom is a link for Certification letter. Click this and print it.
Obtain passport photo, print name on back of passport photo and attach to Certification letter. Bring letter to student affairs and have them sign and stamp.
Mail certification letter to:
National Board of Medical Examiners
Attn: Applicant Services
3750 Market Street
Philadelphia, PA 19104-3102
Few days later you will get an email that tells you that your letter was received and to keep an eye out for another email in the next following days that states you have permission to register.
Go back to above website, click on the Step 1/Step 2 Scheduling link. Pretty straight forward from there on out.
I'm not a senior but just finished this process earlier this week.