I like "Fretboard Theory " 'volume one'..... But I bet Guitar Theory For Dummies" is probably good too.. I like doing everything by the numbers except for the key the music is in, such as 'C', or 'A', etc.. The Greek names for the modes are not necessary at all, imo.. The modes of any scale only relect which number in the scale you start on. In the major key of 'C', the 1st mode would be the notes 'C' through 'C'.. The 2nd mode would be 'D' through 'D'., the 3rd... 'E' through'E', and so on. Each mode has a Greek name, but, as I said, knowing the names is just academic,..ie, memorization without a real purpose. All scales have modes that work the same way.. The mode number is the note in that scale that you start on. The scale could be minor, major pentatonic, minor pentatonic, or any scale you want to study or any scale you might want to make up from scratch... The word "THEORY" is a scary word, imo, and that word probably keeps 90 percent, [?], of players, including me, from attempting to learn it. I found it easy, once I read the first couple of pages.. I needed a teacher after 35 years of playing in bands to help me with what you want to learn. I advise a GOOD teacher to get you started. You have the desire to learn, so that, to me, is 90 per cent of the battle.. I know people who have played 50 years and still don't know more than a few major chords, and possibly a couple minor opnes. They don't have THE DESIRE.. Good luck!