All golfers want to hit their drives farther, but swinging harder is usually not the answer, since you will tend to hit wild shots from the tee.
A simpler and better way to get more distance is to learn how to hit a draw (for right handers). A draw turns the ball from right to left and then rolls a long way once it lands. Close your stance a little so your front foot is closer to the target line. Move your right hand a little under the shaft on your grip. Practice this setup and see if you can get a gentle draw that will roll out to a good distance. With practice, this type of drive will add quite a few yards for you off the tee.