Tap on the circle labeled "C" in the middle of the screen to play a C. A voice marker will appear on top of the note on the screen. To stop the note from playing tap the voice marker. The voice marker will disappear and the note will stop.
Tap the C note to play it again.
To change the octave of the note use a "long press". Touch the voice marker and hold your finger in place for roughly half a second. Now slide your finger up or down on the screen. The voice marker will increase or decrease in size as the pitch of the note jumps down or up by octave intervals.
Tap on the circle labeled "G" to the right of the C to add a new voice. You will hear a second tone and a second voice marker will appear on top of the circle labeled G. You can up to play up to eight notes simultaneously.
Silence both notes by tapping each of the voice markers.
To simultaneously play the three notes in a C major triad tap on the triangle in the center of the screen labeled "Cmaj". Voice markers will appear on top of each of the three notes.
You can silence the triad by tapping the triangle again. Alternatively you can tap each voice marker individually as described above.
Let's play some chord progressions. First play a C major triad.
Now play a G major triad by tapping on the triangle labeled "Gmaj". You will hear the G major triad and the voice markers will move to the notes in the new triad.
Tap the "Cmaj" triangle again to resolve the progression. Then tap the "Cmaj" triangle again to silence the three voices.
It is also possible to trace out chord progressions by tapping on a triangle and dragging your finger across the screen. The voice markers will follow your finger and move to the new notes in the triads as you touch them.
You can manually control the how one chord transitions into another by dragging a voice marker from one note to another. To demonstrate this let's play the following chord progression: Cmaj - Fsus - G7 - Cmaj.
First tap on the triangle labeled "Cmaj".
Now drag the voice marker on the circle labeled "E" to the circle labeled "F".
Now tap on the voice marker on top of the circle labeled "C" and drag it to the circle labeled "B".
Finally tap on the triangle labeled "C".
Tap on the triangle labeled "C" again to silence all the voices.
Voice dragging supports multi-touch try experimenting with dragging more than one note at a time.