What Exercises Should You Do In The Gym To Have A Great Body?

Depends on what you mean by a great body.  There are aerobic exercises and strength exercises.  You do aerobic exercises to increase your fitness, which should reflect in your appearance.  But if you want to bulk up or define your shape more, than you need to concentrate on strength exercises.  Usually you start with exercises that work on a range of muscle groups, and when you become more familiar and experienced with your fitness and strength, then you move onto working individual muscles.  The same goes for aerobic exercises, where you build up the endurance level from an initial starting point.  For a more specific answer, please provide more information about your requirements.