Building chords is one of the simplest concepts to grasp when learning to play organ or piano. To build chords, you don’t need to know how to read music; the simple chart below will help, plus a little basic music theory.
The first thing you need to do is identify middle C, as we’ll make that the root note of all the chords described here. Middle C is in the center of your piano, immediately to the left of two black keys.
Second, you need to know that the distance between any key on a piano is a “half-step.” Going from white key C to the next white key D is a whole-step because a black key is in the way. This black key represents a half-step—it is C#. A half-step higher than C# is D (the next white key) and another half-step will take you to the black key D#. By this logic, a half-step higher than E is E#, right? Wrong—you’ll notice there’s no black key in the way here, so the next half-step is the white key of F.
Building chords is simply a matter of describing the distance in half-steps between notes. The easiest chord to play is the chord of C Major. This chord begins with middle C. You then go up four half-steps to E and another three half-steps to G—the notes of this chord are therefore C-E-G, and the formula is Root-4-3. (Play it, it makes a beautiful sound!) The same formula works to make other Major chords. The chord of F Major is R-4-3, or F-A-C. The chord of D Major is R-4-3, or D-F#-A.
The chart below shows how the same formula can be applied to other “flavors” of chords. The names of these chords can be intimidating, but the formulas are simple: again, they simply describe how many half-steps you take from your root note up the keyboard.
For instance, the chord flavor called a “seventh” uses four notes instead of three. Its formula is R-4-3-3, or, if C is the root note, it’s C-E-G-A# (or Bb). This is the chord called C7. Properly speaking the A# is Bb—remember, all the black keys have two names, either the sharp of the note they follow or the flat of the note they precede.
—adapted from Play Piano in a Flash, New York, Hyperion, 2004.