Harmonic minor is an natural minor scale with a raised 7th. If you know the minor scale, all you have to do is change that note. Example - For a G minor scale, raise the 7th tone, F, to an F#.

It's the minor third interval that give it that "bad to the bone" sound and makes it resolve more strongly to the root.



|--------------------------------|
|-------------------------7-8----|
|-------------------5-7-8--------|
|-------------4-5-7--------------|
|-------3-5-6--------------------|
|-3-5-6--------------------------|