Some will argue that the pecs are one muscle and you can't really focus on one part. I like to hit my chest from different angles and I definitely feel it in different parts. I do the bench press for overall development, incline bench for upper pecs and decline bench to focus on lower pecs. Then mix it up some more by switching to the same 3 bench positions but use dumbells, presses or flyes or both. For me the real key is variety. Now go pound some iron and have fun.