If you get protection for your work without actually registering it, then why would you register it? In most cases you won’t. The only value there is in a registered copyright is that it gives you the right to sue someone for infringing on your copyright (likely quoting from it without permission or without giving you credit). If we are talking about articles, unless you were paid top rates for those pieces, there usually is not enough money involved to justify a suit. Even with a book, unless someone has made it into a movie or infringed on the merchandising rights, there still isn’t enough money at stake.
If you register before or within 5 years of publication, you have established the validity of your copyright in case you want to sue. If your registration is made within 3 months after publication or prior to the infringement, if you win, you can collect both statutory damages and attorney’s fees. You can actually register your copyright after an infringement, but if you do you can only collect actual damages or lost profits—no attorney’s fees.
To register a copyright you can order Form TX from the copyright office by mail, or go to their Website and copy off that form. Their contact information is as follows:
Copyright Office, Library of Congress, 101 Independence Ave. SE, Washington DC 20559-6000; 202-707-3000; http://lcweb.loc.gov/copyright. You will also find additional details about copyright on their Website. Check Website for current fee for registration