What does it mean by harmonizing melody? It means to create accompaniment to the main melody based on chord progressions. In piano, your right hand usually plays the main melody and your left hand accompanies the right hand. Once you master the techniques of harmonizing melody, you can add your desired style and texture to the music, as I’ve discussed in previous articles.

The three chords that you MUST know are I, IV & V (or V7). These three chords contain all the notes of a major scale. Take C major for example: 

As you can see, you have all C, D, E, F, G, A, B from these three chords. 

Refer to following chart as a guideline to determine which chord is usually used with the melody notes of major scale. There are notes, e.g. scale degree 1, that you have more than one chord to choose from. Your ear should be the guide. Listen to the song again to determine which chord fits better.

I like to show you examples of C Major Scale. 

Example 1: C major harmonize with chord I, IV, V, I (Listen)