You can do this workout sitting down for least resistance on your legs and to concentrate more on biceps.
If you do this movement standing up, your knees must be bent a bit as you curl the weights upward.
Anyway, begin with your starting position – standing or sitting down with the dumbbells on your side.
Instead of the regular dumbbell curl, twist your wrist so that your palms are facing each other.
Lift the weights up while your triceps are close to your body.
Release it down to starting position.
(Use the right dumbbell weight because if you force upon yourself a heavier weight, you will get injured.)