The chord G#/B that is shown here contains the notes: B, C, G#. The root of the chord is G# (The lowest sound - the bass - is B). The scale from which the chord is derived is Major, and the degrees of the scale are: 1, 3, 5.
To play the chord G#/B shown above, place your fingers as follows:
On string number 4 (the thickest), on fret number 4
On string number 3, on fret number 0 (open string)
On string number 2, on fret number 4
On string number 1 (the thinnest), on fret number 2