Q: What are some cool ways to harmonize a melody?
A: on 'old macdonald had a farm', let's say it's in C, you could add "f f e" notes above "had a farm" (a sixth up, in the key). Also on "happy birthday", on the last line ('happy birthday to you'), again let's say it's in C, you could put these notes under the melody: happy(Ab), birth(G), day(F#), to(F), you(E)