I haven't actually read the Secret, in fact I just heard about it, but it supposedly is based on the works of Wallace D. Wattles, a 19th century writer of self-help books, including the awesomely titled Science of Being Great. His methods are basic Hermetic Philosophy applied to material concerns like health and money, and they work, at least for me (although I'm not rich and my greatness is up for debate). The basic method is to constantly visualise what you want to succeed at and build up a successful vibration that draws all this to you.
You can get his books cheap on Amazon, and a few can be had for free in PDF from internet self-help gurus if you want to sign up for spam. He is very popular with the internet self-help crowd because he was relatively obscure and his works are public domain, and therefore free to chop up into overpriced eBooks.