7 CFR 800.33: How to register.

Any person who is required or desires to register must submit an application for registration to the Service. Application forms can be obtained from the Service. Each application shall: (a) Be typewritten or legibly written in English; (b) include all information required by the application form; and (c) be signed by the applicant. The information required by this paragraph may be submitted to the Service via telephone, subject to written confirmation. An applicant shall furnish any additional information requested by the Service for consideration of the application.