Download a SR application from the Copyright Office's official website (see references).
Gather all of the required materials you will need to send to the Copyright Office. This includes a sound recording of your beat and the fee required. As of June 2009, the fee is $45. You can send a money order or check, made out to Register of Copyrights.
Print out the form and complete it. Send it back to the Copyright Office with all of your other materials.
Wait for your application to be processed. Once it is processed, you will receive a certificate in the mail. This can take up to six months although your beat is copyrighted as soon as the Copyright Office receives it.
Publish your music.