The Picardy Third cadence is a major triad in a minor key with Nonharmonic tones in the cadence

When i use a Picardy Third Cadence?

Why would i use a picardy third cadence?

How do i use Non-Harmonic tones in the cadence?

Non-harmonic tones would be the 2,4,6,7 degrees of the key/scale im in?