>There is no office where you file a copyright application. Using a (c) and/or other types of copyright notices is optional in a post-Berne American court.
Copyright is given de facto, but there is in fact an office where you file for a registered copyright.
In general, copyright registration is a legal formality intended to make a public record of the basic facts of a particular copyright. However, registration is not a condition of copyright protection. Even though registration is not a requirement for protection, the copyright law provides several inducements or advantages to encourage copyright owners to make registration...[1]
The office in question is the US Copyright office. Registering gives you benefits such as damages and attorney's fees in the event of a court action.
[1] http://www.copyright.gov/circs/circ01.pdf