Welcome to my lesson on chords. Improvisation is something that doesn't have to be performed solely with single notes - its also possible to improvise with chords. In this lesson, we focus on what is termed "Quartal harmony" - that is the stacking of 4th intervals within a scale or mode. In this case, we are stacking 4ths within C Dorian mode.
I start by finding the lowest note within the C dorian mode on a string of my choice, for example, the D string - the lowest note within the mode is the open string itself - the note of D is the 2nd degree of C dorian. Then we find the 4th up from that note (again within the C dorian mode) the diatonic 4th of D is G which happens to be the Open string adjacent. Next we find the 4th up from that and so on.
We end up with a chord built of stacked 4ths, then we figure out how this chord will move up to the next scale degree.
Have fun and be sure to learn the shapes well before improvising with them.