:00 in the this video
Probably the most widely known "chest" exercise, the Bench Press is the meat and potatoes of any upper-body training program focused on size development.
The Bench Press mainly targets the chest, shoulders and arms.
However, when performed properly by driving the legs and bracing the core, the Bench Press actually becomes something of a full-body movement.
How to Perform the Bench Press
Start by lying on the bench with your hands on the barbell at about shoulder width apart (possibly wider or narrower depending on arm length). It's important to grip the barbell as hard as you can to increase tension in the upper body as well as prevent it from slipping.
Lift the barbell out of the rack and lower it under control to the chest until it lands softly right on the sternum.
When resting on the chest, the barbell should make a straight line connecting one nipple to the other.
The arms should be positioned at 45 degrees from the body so as to make sure they don't flare out too wide.
Once the barbell touches the chest, forcefully explode and drive it to the top position with the arms fully locked out.
Important Note: your shoulders should be retracted (pulled back) throughout the whole movement to take stress off of the shoulder joint and provide a solid base on the bench.