“I am interested in learning more about the diatonic scale, how it is built and how to harmonized it. I would also like to know what the difference is between major and minor diatonic scales.”
The term “Diatonic” means “of the scale” and usually refers to the major scale. When notes of a piece of music are all drawn straight out of the key’s major scale, musicians say the notes are diatonic. When notes fall outside of the scale, musicians say the notes are non-diatonic.
Major scale patterns are taught in my book Fretboard Theory chapter 5 and its related video program. Other book chapters and video segments get into the details of combining major scale notes to form chords, and putting the chords in various orders to compose chord progressions (or chord changes). You can also use the diatonic major scale to add added chord tones and extensions to chords, and play intervals.
The minor scale is simply a mode of the major scale. When you build chords using major scale tones, the chord built on the 6th degree is naturally minor. When music uses the major scale but centers on the 6th degree, it creates a minor sound quality called Aeolian mode, better know as simply the minor scale or the relative minor scale.
This is all fundamental music theory stuff and covered at length in Fretboard Theory.