Now I'm no expert, but as I understand it (and according to http://www.unc.edu/~unclng/public-d.htm), copyright exists once the work is fixed in a tangible medium...which means the copyright symbol, your name and the date on your chap is technically all you need. However, registration of copyright is encouraged as a more defining statement of ownership.
Registration is helpful IF you should ever run into any problems. It provides a clear date as to when the copyright was assigned to you. Just having the copyright symbol is not necessarily enough to establish WHEN you actually set the work in a tangible medium, although one trick I've heard is to mail yourself a copy of your chap after having signed your name across the flap of the envelope. Don't open it so that the postmark provides a defining date.
If you do decided to register that book, you do it through the copyright office...There is a fee and paperwork to fill out. Yes, there have been instances where somebody's work has been ripped off...will that happen to you (and will you find out about it)?...unlikely.
Hope I haven't been too confusing in my explanation.