Do your best to ensure your piece of music is completely original, both melodically and lyrically, as it is illegal to attempt to copyright a piece of music derivative of a previously copyrighted piece of music.
Upload the piece of music as an MP3 file on your hard drive.
Go to the United States Copyright Office website (see Resources) and click on the "Electronic Copyright Office" icon under the "How to Register a Work" heading.
Continue to the Electronic Copyright Office.
Register for a new account at the Electronic Copyright Office unless you have registered a piece of music before and already have an account.
Log in to your account at the Electronic Copyright Office.
Start a new claim. Click on the "Type of Work" window and select "Performing Arts."
Enter as much information as you can regarding the piece of music you want to copyright, such as the author, year of creation and whom to contact in the case of a discrepancy.
Enter your credit card information to pay the registration fee. The fee to copyright a piece of music is $35 as of 2010.
Locate the MP3 of your piece of music on your hard drive and upload it to the Electronic Copyright Office system.