All major and minor chords are triads. ... Here's the 3 major triad shapes on the top 3 strings, using D as an example for the frets numbers. With these three shapes, you can play EVERY major chord on the guitar. All you have to do is slide it to the correct root note to get the chord you want.
What frets are used to play the A chord?
Here is the standard way to play an A major chord in the open position: - Index finger on the 2nd fret of the D (4th) string. - Middle finger on the 2nd fret of the G (3rd) string. - Ring finger on the 2nd fret of the B (2nd) string.
How do I know what fret to use?
If you see a rectangular block at the top of the diagram, that just represents the nut of the guitar. If you don't see the nut you will probably see a number to the left of the diagram that indicates what fret you should be on. An X above one of the strings means that you should mute or just not play that string.