Probably the best way to learn to use seventh chords is to insert them between triads so that the seventh resolves in the next triad. A good example of this is to go Dm–Dm7–G (see Figure 21.10).
In this context, the seventh of the chord ii (note C) appears as a passing note between two triad notes—the D of the Dm triad and the B of the G triad. When you are familiar with this type of progression, you can attempt to create chord progressions in which all of the chords are seventh chords. You should use the principles of root movement to assist this process.