Even out your back, one arm at a time.
Keep your torso square and resist twisting toward the working side.
Rowing a band from a waist-height anchor with one arm trains your back through a horizontal pull while your torso fights the rotation the load creates. Your lats and mid-back drive the elbow back, your biceps assist the pull, and the band adds a hard squeeze at the very end where rows usually taper off. One side at a time means no hiding a weaker pulling arm.
Straight back along your ribs, not out to the side. Finishing with your elbow past your torso and the shoulder blade squeezed is what loads the lats and mid-back. A flared elbow turns it into a rear-delt drill.
Same one-sided pull, opposite resistance curve. The dumbbell is heaviest at the stretch, the band is heaviest at the squeeze, so band rows teach you to own the contracted position. They pair nicely if you have access to both.
A small forward reach at the bottom is fine, but the rep should be won by your back, not by winding up and unwinding your spine. Keep the hips and shoulders mostly square and let the shoulder blade do the travelling.
