Open D tuning requires the sixth, second and first strings lowered one tone as well as the third string lowered one semitone. This can be done in four steps.
Option 1:
Place a left hand finger on the sixth string at the 7th fret (a B note), and play the string. Play the open fifth string (an A note). Turn the sixth string tuning key slowly in a clockwise direction, lowering the pitch of this string until the note on the 7th fret is the same pitch as the open fifth string. The note on the 7th fret will now be an A note and the open sixth string will be a low D note.
Option 2:
Place a left hand finger on the sixth string at the 12th fret (an E note), and play the string. Play the open fourth string (a D note). Turn the sixth string tuning key slowly in a clockwise direction, lowering the pitch of this string until the note on the 12th fret is the same pitch as the open fourth string. The note on the 12th fret will now be a D note and the open sixth string will be a low D note.
Option 1:
Play the note at the 4th fret, fourth string (an F# note). Play the open third string (a G note). Turn the third string tuning key slowly in a clockwise direction, lowering the pitch of this string until the open string note is the same pitch as the 4th fret, fourth string. The open third string will now be an F# note.
Option 2:
Play the note at the 9th fret, fifth string (an F# note). Play the open third string (a G note). Turn the third string tuning key slowly in a clockwise direction, lowering the pitch of this string until the open string note is the same pitch as the 9th fret, fifth string. The open third string will now be an F# note.
Option 1:
Play the note at the 3rd fret, third string (now an A note). Play the open second string (a B note). Turn the second string tuning key slowly in a clockwise direction, lowering the pitch of this string until the open string note is the same pitch as the 3rd fret, third string. The open second string will now be an A note.
Option 2:
Play the note at the 12th fret, fifth string (an A note). Play the open second string (a B note). Turn the second string tuning key slowly in a clockwise direction, lowering the pitch of this string until the open string note is the same pitch as the 12th fret, fifth string. The open second string will now be an A note.
Option 1:
Play the note at the 5th fret, second string (now a D note). Play the open first string (an E note). Turn the first string tuning key slowly in a clockwise direction, lowering the pitch of this string until the open string note is the same pitch as the 5th fret, second string. The open first string will now be a D note.
Option 2:
Play the note at the 12th fret, fourth string (a D note). Play the open first string (an E note). Turn the first string tuning key slowly in a clockwise direction, lowering the pitch of this string until the open string note is the same pitch as the 12th fret, fourth string. The open first string will now be a D note.