Take a shoulder-width stance and grab the weight at the handles. Firm up your torso with your pelvis in a neutral position.
From the starting position do the motion by contracting the upper trapezius muscles, namely elevating your shoulders (lifting arms upwards). Exhale after making the motion downwards and go back to the starting position and inhale. Do the required number of repetitions.
Watch for the correct starting position. Fix the thoracic muscles and the position of your pelvis to avoid lumbodorsal swayback and undesired backwards bending.
Exercise in front of a mirror to make sure you are using the correct technique.