Never mind you guys. I think I found out what I was looking for, I found an answer from this website
http://mugglinworks.com/chordmaps/part1.htmI high light the bold area that gave me understanding.
Intersection
At this point, you might think we should learn a lot about scales, and someday I hope you can. But for now, we need to stay true to our purpose: to know the chords we need and how they flow from one to another. So let's move on.
It might surprise you, but it's possible to write a very good song without knowing a lot about scales.
When you play a chord, you can immediately hum several notes that seem to fit. This process of playing and singing while searching for a strong melody is automatic. You "hear" the vocal lines in your head, or you experiment until you discover something you like. Part of the fun of writing songs is this searching process.
But while you can get along fine "discovering" the tune, it's a lot harder to discover chords. The writing process is much easier if you already have a group of chords to work with.
-----------------------------------------------------------------
So my point is now that I have found a chord where I hum the melody what is the next step? Is like figuring out what scale to play over the hum chord?