The chords relative to any key are made up off the 7 notes of the relative scale. Dropping the third of a chord a semitone (1 fret or piano key) is the difference between a major or minor chord. this is how you fit them in to a normal 7 note scale, all chords should fit into the scale unless it's an accidental or a key change. Clear as mud?
Can you please explain in pidgin Engrish?