Most chords are notes 1, 3, 5 of the scale starting on the bottom note of the chord, so you can use those to play major and minor triads (3-note chords).
For example - C E G - C chord, F A C - F chord
7ths are - 1, 3, 5, 7
6ths - 1, 3, 5, 6
hope this helps...