How do you play melodic on the piano?

Answer 1

What do you mean by this? If you mean a melody, it's the main tune. You play it either by ear or reading music.

Or do you mean melodic minor scales? There are 2 types of minor scales; melodic and harmonic. I apologize if you are not familiar with Music Theory and don't understand what I am saying, but there are harmonic and melodic minor scales.

Harmonics involve the key of the scale, plus the raised 7th note ascending and descending.

Melodics are also the key of the scale, but with the 6th and 7th notes of the scale raised when ascending, and back to the raw form of the key when descending.