Here's a quick and dirty lesson on securing a copyright that I worked up for my brother-in-law who is working on a book:
Copyright is automatically assigned to you by law from the moment you set pen to paper or otherwise record your creative work. But, there are some things you can do to protect yourself further if you feel the need:
First on all copies that you send out, provide notice of copyright:
The notice for visually perceptible copies should contain all the following three elements:
1. The symbol © (the letter C in a circle), or the word "Copyright," or the abbreviation "Copr."; and
2. The year of first publication of the work. In the case of compilations or derivative works incorporating previously published material, the year date of first publication of the compilation or derivative work is sufficient. The year date may be omitted where a pictorial, graphic, or sculptural work, with accompanying textual matter, if any, is reproduced in or on greeting cards, postcards, stationery, jewelry, dolls, toys, or any useful article; and
3. The name of the owner of copyright in the work, or an abbreviation by which the name can be recognized, or a generally known alternative designation of the owner.
Example: © 2002 John Doe (www.copyright.gov)
Note: Some people try to just use (C) as a copyright symbol which is not sufficient.
Next, seal a copy of your work in an envelope and send it to yourself via registered mail/return receipt requested. When the envelope comes, do not open it, but store it unopened along with the return receipt in a safe place. This will provide proof that you created the work prior to a certain date.
Finally, you can register the copyright through the copyright office. The forms are available online and it costs $30.00 to register your work. However, if you provide notice of copyright and retain proof that the work is yours, registering isn't all that necessary. You can always go back and retroactively register your work if a problem comes up. Don't bother with the copyright registration companies that you see on the web. They're ripoffs and do exactly the same thing you can do yourself. Most times, when you find someone to publish your articles or book, they will handle the copyright registration, though in the case of articles or short stories, you might want to have the rights reassigned back to you after publication. Here is a good FAQ site for copyrights.