If you have trouble understanding a point of musical theory, you might try
Wikipedia.org.. Sometime a different explaination is more understandable..
i.e.; circle of 5th..

http://en.wikipedia.org/wiki/Circle_of_fifths

Actually just a web search can bring a mass of information..

http://xenophilius.files.wordpress.com/2008/11/circle_of_fifths_and_color_wheel.jpg

BTW, Guitartricks does have it's own search engine (search box)

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