To do this tutorial, you need to know your major and minor triads really well, in different inversions, plus your major and minor 7ths, and tones and semitones.
To construct a “dominant” 7th chord (major triad with a minor 7th):
- play the root in the LH
- play the major triad in the RH in any inversion
- move the tonic in the RH down a tone
To construct a minor 7th chord:
- play the root in the LH
- play the minor triad in the RH in any inversion
- move the tonic in the RH down a tone
To construct a major 7th chord:
- play the root in the LH
- play the major triad in the RH in any inversion
- move the tonic in the RH down a semitone