Chances are you're going to need a class sooner or later. Just be sure to pick a reputable one, whether it's online or off. The classes allow someone experienced to give you practical, guided aid in learning, and to help you develop your own energy to better work with Reiki. Trying to teach yourself anything beyond basic Reiki from books and articles is like trying to teach yourself martial arts from books and articles; you might succeed, but you also might never know where you're erring and pick up a lot of bad habits along the way.
You can probably snag e-books for free and learn the history, some basics, etc, if you're not opposed to such an idea.
EDIT: If you're into spiritual/energy healing in general,
Qigong(<--link) is also nice. There's a lot more content available for it, too, including videos.