A chord will sound, played either melodically (one note at a time) or harmonically (all the notes together). Select your answer from the given chord choices. To hear the chord again press the "Play" button at the top of the screen.
If you make a mistake the program will display both chords in staff notation, with your choice below the right one. You can use the "Hear your choice" button to compare the two.
The program will gradually work through various contrasting pairs such as major vs. minor as you show mastery of their differences. After you've shown success with each distinction it will eventually mingle all the triads, so that you may be hearing any of them.
To enter Practice Mode touch "Practice" at the top of the screen. Points are not counted in practice mode and you can choose the chords you want to learn. You can also choose whether you want to hear the chords played melodically or harmonically or whether to allow inversions. To bring up the practice window again touch "Change practice choices" above the selection boxes. To leave practice mode touch "Exit Practice" at the top of the screen.