Stand with your feet hip-distance apart. Hold a dumbbell in each hand so your palms face in toward the sides of your body.
Start with the right side first. With control, keep your arm straight (but don't lock that elbow) and as you inhale, raise your right hand up toward the ceiling. You want your palm to be facing down and your arm to be parallel to the floor. Then as you exhale, slowly lower your hand back to your body. You should be able to see your hand in your peripheral vision. Your arm won't be directly out to the side but slightly forward.
Do the same move with your left arm.
Then do both your right and left arms at the same time to complete the rep.