To change a natural minor scale into harmonic minor scale

Answer 1

The simple answer is raise the 7th note in the scale by a half-step.

If we look at C minor, the natural minor scale is C D Eb F G Ab Bb C.

To go to a C harmonic minor the Bb becomes a B-natural: C D Eb F G Ab B♮ C

Again, to change from natural minor to harmonic minor, raise the 7th note of the scale by a half-step.