My friend wrote a little riff and wanted me to harmonize it, I'm relatively new to theory, but I thought I took a good approach, apparently not.

I noticed his melody was in C minor. So I thought I would Harmonize it in Eb Major, because they have the same notes.

C Minor: C D Eb F G G# Bb C
Eb Major: Eb F G G# Bb C D Eb

So I went through his riff and every time I saw a C, I would play an Eb. D an F, Eb a G....and so on. Well this sounded like shit. can anyone explain the proper way to do this?

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