Place your index finger across all six strings at the 2nd fret
Place your ring finger on the 4th fret of the D string
Place your pinky on the 4th fret of the G string
Place your middle finger on the 3rd fret of the B string
Strum from the A string down, or all six strings if the low E string rings clearly
Keep your index finger pressed firmly to create the barre
Make sure each string rings cleanly without buzzing
Use a Bm barre chord shape based on the A minor form
Alternative shape: place your index finger on the 2nd fret of the A string
Place your middle finger on the 3rd fret of the B string
Place your ring finger on the 4th fret of the D string
Place your pinky on the 4th fret of the G string
Mute the low E string in the alternative shape
Practice shifting the shape up and down the fretboard to build strength