You'll identify by ear various chords in a short progression invented by the computer. The music is not shown at first, just a box for each chord name. Use the "Play" button to hear the chords as many times as you like. To enter your answer select from the displayed chord choices (listed in Roman numerals) and then touch the box where it belongs until all the boxes are filled. To change your answer, just select a different chord and follow the same procedure. When you're ready, touch the "Check Answer" button. The correct numerals will be displayed along with the music.
To enter Practice Mode touch "Practice" at the top of the screen. In Practice Mode your scores are not recorded, and you can choose the length of the example, whether or not it should begin on the tonic chord, whether you're going to be asked to distinguish inversions (e.g. specifying that a chord was a IV6, not just a IV), and which chords you want included. The list of possible chord pairs includes more advanced choices such as secondary dominants, the augmented sixths, and various types of seventh chord movement. 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.