The chord Bbm/F# that is shown here contains the notes: Gb, Bb, F. The root of the chord is Bb (The lowest sound - the bass - is F#). The scale from which the chord is derived is Minor triad (1–♭3–5), and the degrees of the scale are: 1, ♭3, 5.
To play the chord Bbm/F# shown above, place your fingers as follows:
On string number 3, on fret number 6
On string number 2, on fret number 6
On string number 1 (the thinnest), on fret number 8
Start strumming from string number 3 (notice not to play string 4).