As you start, your feet should be placed shoulder-width apart and holding a pair of dumbbells at arm's length (1).
Then, lift your arms until they're parallel to the ground while keeping a slight bend in your arms (1). Pause, slowly lower, and then repeat (1).
Recommended tutorial: https://www.youtube.com/watch?v=3VcKaXpzqRo
(1) The Men's Health Gym Bible by Myatt Murphy and Michael Mejia