Increased cross-sectional area and size of a muscle and its fibers is called hypertrophy. Any kind of resistance training will cause some hypertrophy in the muscles. To train specifically for hypertrophy you must do exercises with heavy weights (60-80% of your 1 rep max). The volume of the exercises should consist of 4-8 sets and between 6-12 repetitions. You also must eat an increased load of calories to allow your body to build upon its self.