The chest fly is a great exercise to strengthen and tone the muscles of the chest. It works a combination of the chest, shoulders and biceps.
Lay on your back on a bench with your feet planted firmly on the floor. Adjust the bench height if necessary.
Hold a dumbbell in each hand, with your palms facing each other, above your chest. Maintain a small bend in the elbows throughout the exercise.
Move your arms apart, leading with the elbows, until they are just below the level of your shoulders. Maintain control throughout the lowering phase.
Return to the starting position slowly maintaining control. Repeat.
For when progressing try using an incline bench to place more emphasis on the upper chest.