Sit down on a flat bench with a dumbbell resting on each knee. Hold the dumbbells so that your palms are facing each other. Lie back on the bench, holding the dumbbells in your hand very close to your chest. Ensure that your back is flat on the bench and that your feet are flat against the floor. Extend your arms towards the ceiling (both palms still facing each other) until they are nearly straight and the dumbbells are directly over your chest. Slowly lower the weights outwards (as if you are drawing an arc in the air). Continue to keep the elbows slightly bent and continue lowering the dumbbells outwards until your elbows reach (or nearly reach) the same level as the bench. Slowly bring the weights back up into the starting position via the same arc. As you perform this portion of the lift, focus on squeezing the pecs in order to bring the weights back together above your chest. Hold the weights above you briefly upon completion of the repetition and continue to keep the chest muscles squeezed before beginning the next rep.
When you have completed your prescribed number of repetitions, lift your legs from the floor, twist your wrists so that your palms are facing one another, and touch the bottom of the dumbbells to your thighs. Then, perform a small kick forward with your legs so that you are sitting up with the dumbbells on your thighs. This will allow you to place the dumbbells back on the floor in a controlled fashion.