The 2-0-1-2 diagram uses standard re-entrant tuning (g C E A). From string 4 to string 1 it sounds A, C, F and B: the ninth, eleventh, minor seventh and major third of G11. The root G and fifth D are omitted; this four-string voicing does not sound all six theoretical chord tones.
Put your index finger on the E string at fret 1, middle finger on the g string at fret 2 and ring finger on the A string at fret 2. Leave the C string open and arch your fingers so it can ring without being touched.
Pick g, C, E and A separately to check the open C, then strum all four lightly. The C and B are a semitone apart in pitch class, giving this voicing a close, tense colour; try it with a bass player sounding G to hear the missing root underneath.