Lie on a flat bench holding dumbbells at arms length aboveyou.  Bend your elbows slightly, with your palms facing each other.  Lower the dumbbells out and down in a wide arc as far as possible,stretching the pecs to the maximum.  Return the weights to the startingposition in the same wide arc.  Do not press them.  Imagine hugging atree.  It will help you keep the correct form.