Technically, your song is copyrighted as soon as you finish writing it. However, you’re going to want to register that copyright to protect yourself in case someone tries to use your song without your permission. You can download copyright registration forms from the Copyright Office at www.copyright.gov/forms, or you can call the Forms Hotline at 202-707-9100, or write to the Copyright Office, Library of Congress, 101 Independence Avenue, S.E., Washington, DC 20559-6000. The cost to file Form PA is $30.