You can Register your work online at http://www.copyright.gov/
What is copyright?
Copyright is a form of protection grounded in the U.S. Constitution and granted by law for original works of authorship fixed in a tangible medium of expression. Copyright covers both published and unpublished works.
What is poor man’s copyright?
The practice of sending a copy of your own work to yourself is sometimes called a “poor man’s copyright.” There is no provision in the copyright law regarding any such type of protection, and it is not a substitute for registration.