Muscles worked:
Pectorals (specifically targets upper chest), deltoids, triceps.
Execution:
Set an adjustable bench at a 45 degree angle. You may adjust the bench at a more steep angle but as a general rule, the more closer to a 90 degree angle, the more your shoulders will be worked. The lower the angle on the bench the more of the lower chest area will be incorporated. Most incline bench presses are already manufactured at a set 45 degree angle. On the incline bench press, grasp the bar with a grip where the arms are wider than shoulder width. There are usually lines engraved into the bar that are used as a reliable way to ensure even hand spacing. Depending on your shoulder width, usually your ring or index finger will be placed on the line. Lift the bar off the upright support pegs. Slowly lower the bar toward the upper chest/clavicle area. It's important to note that with a full textbook range of motion, the bar will touch the upper chest. However, depending on shoulder mobility and range of motion, you may have to perform the rep with a range of motion that does not cause pain or injury. From the bottom of the range of motion, contract the pectoral muscles and push the bar back up to the starting position. You may also do an incline barbell press on the smith machine which will allow for greater safety and also more weight to be used which allows for more muscle stimulation and growth. The same execution of the rep is to be completed with the dumbbell incline chest press. However, instead of bringing the dumbbells to the upper chest they will be lowered to the upper side chest region.
Bonus Round: By adjusting your hand spacing, you can effectively change the focus of the exercise. The more narrow you place your hands on the barbell, you will target more of the inner upper chest, shoulders and triceps. A wider grip will give a mechanical advantage allowing to lift more weight.
*These principles also apply with the flat bench as well. Use a "spotter" when performing this exercise for added safety.
** As always, consult your physician before beginning this and any other exercise program. Consulting a CERTIFIED personal trainer for a demonstration on proper technique is strongly encouraged. If you feel pain and/or discomfort, stop the exercise and consult your physician... have to throw in the disclaimer!