The D#9 chord (dominant 9th): notes D# G A# C# F, degrees 1 – 3 – 5 – ♭7 – 9. Guitar shapes: xx1021, x63643, x6566x, 11-8-8-8-8-9.
A chord is the root plus degrees above it, most often stacked in thirds. Major and minor differ only in the lower third: a major third (M3) sounds bright, a minor third (m3) sounds sad. Pick a chord and a root to see its degrees and intervals, and its shapes.
m — minor, M — major, P — perfect, A — augmented interval; the number is the degree count. m3 is 3 semitones, M3 is 4, P5 is 7
D# D#m D#5 D#7 D#m7 D#maj7 D#sus2 D#sus4 D#add9 D#6 D#m6 D#9 D#dim D#dim7 D#m7♭5 D#aug