The internet site http://www.musictheory.net is a free, animated, interactive site that is good for basic music theory. Give it a try, with or without any printed book.
My problem with Eddley’s book is that it goes into jazz chords pretty early in the game. Since theory and harmony are the bane of my musical existence, I needed something very fundamental.
I don’t know the “Idiot’s” or “Dummies” theory books, but some of the other students in my basic Theory college level course liked it quite a lot.
I have not had any luck hunting down the Kathy Bundock Moore harp theory books there were mentioned on this post. If anyone has any luck and can share where they found them, I’d appreciate it. Thanks!