Help understanding chords
I've attached a snip of a song I'm working on - "High Barbaree" I'm a beginner playing an English Concertina - the 30-key Jackie. On the music you will see that it includes 3 guitar chords, starting with Gm, Cm and D7.
I"ve seen the chord charts that show chord structure for the English and from it I see that on my Jackie, there are 3 different combinations of Gm. Same with the other two chords. Which one would I pick to play the first part of this song, and why?
BTW -
A chord is 3 or more notes that harmonise.
(I will use upper and lower case to show the same note in different octaves: C is an octave lower than c, for example.)
A simple chord is made of notes 1, 3 and 5 counting 1 as the root of the chord.
So the chord of C major is made up of the notes C E and G.
When a chord is major, the interval between the root and the 3rd note (C and E in the example) is 2 whole tones, and the interval between the 3rd and
