The pecs are separated into two muscle groups Pectoralis major and pectoralis minor. The majors function is to bring the humerus across the chest ( like a chest flye) The minors function is to move the shoulder forward.
One of my favorite chest exercises is the dumbell press on a flat bench (pec major) or an incline (pec minor). The use of dumbells allows for unilateral training as well as allows the shoulder joint a natural flow of movement. On a flat barbell bench press the shoulder joint has to make a visible comprimise to follow the path of motion created by the straight bar.
As far as secondary exercises Flyes (same flat and incline) put the muscle in a very good anatomical position for maximal contraction.
your chest work out - the machine where u push out is call chest press, which has a very similar bulking affect on the chest as does your other exersize the bench press. A good chest workout would train upper chest and a definition exercise, such as flyes. EX: ( in this order ) Bench Press, flyes, incline bench.
Depending on your prefered volume, you could add in exercises that train the lower chest, or furter define the chest.... such as decline dumbell or barbell press to bulk and flyes, cable crossovers and chest dips for definition. Training the lower chest gives you that line towards the bottom of your pecs which looks appealing, and using flyes gives your chest a more complete look.
So, overall, Anything on an incline bench will train the upper part of the chest, anything on a decline with train the lower part of the chest.