Sit on end of bench with legs far apart. Grasp dumbbell between legs with arm vertical under shoulder. Position torso slightly forward with hand on knee for support.
Pull dumbbell to front of shoulder with elbow leading out to side. Allow wrists to flex as dumbbell rises upward. Lower and repeat.
When dumbbell is raised, wrist should be in front or just below of shoulder; elbow should be to side, not too pointing forward. See Upright Row Safety. Also see Dumbbell One Arm Upright Row in standing position.