If you learn from books, there's Parks' book noted above, and Twist of the Wrist by Keith Code, and numerous others. Code was the original in the motorcycle training world. Several tutorials are available in video versions.
Ultimately, even if you read the books, and practice the techniques, you'll get a lot more from a class. In addition to Code's California Superbike School, there's Reg Pridmore's CLASS school, and Jason Pridmore's STAR school. CLASS and CSS both offer schools around the country at different tracks. CLASS is more of a street oriented school, CSS is more race oriented, more technical and had better instructors. Both have a lot to offer, and will make you a better, faster and safer rider. I attended CLASS twice, and CSS three times, and IMHO, CSS is the better of the two once you're past the basics.
Beyond the organized track schools, most trackday organizations offer instruction. Quality varies greatly, but you can get a lot for your money, as trackdays are usually only 1/4-1/3 the price of a one day track school.
My advice would be to read some books, then go to a nearby trackday that offers instruction. Do trackdays for at least a year before getting serious about actual racing, and if you can afford it, attend a couple of actual schools. Most regions offer 'club' level racing, which will generally require joining an organization, and obtaining a race license (proving you can navigate the track without wiping out yourself or someone else).
We haven't talked about bikes, but starting on a smaller bike (600) will help you build skills. The modern literbikes are ridiculously powerful, and it's much more difficult to approach the limits of the bike. The 'parking lot' racing you saw was likely Super Motard racing, which is pretty popular. Looks like a lot of fun, but I don't have any experience with it, so I'll let someone else comment.
