As soon as they are created, all works are protected by statutory copyright. BUT, even though we have statutory copyright, there are some good reasons to register your work with the U.S. copyright office, including:
(From Tad Crawford's, Legal Guide for the Visual Artist).
You can use snail mail to request a copyright kit from:
Copyright Office, Library of CongressYou can view information on their website and download the forms you need by going to:
Washington D.C. 20559