Shaping golf shots is important to lower your scores. If you can master the various trajectories of the golf ball, then you should be able to play under the worst of conditions and circumstances. Most golfer strive to hit the ball straight. This is a huge mistake. Straight is the hardest shot in golf. I mean think about this. There is always spin on the ball, its not like throwing a knuckle ball. So, a fraction off center the ball may spin left or spin right, depending on the club face.
Most pros on tour have a preferred shot shape. More than likely its a draw, since its the shot shape that is more powerful and travels farther. Although, there are plenty of guys out there that hit big high long fades. Just look at Freddy Couples, for instance. The point here is that if you have a shot shape, don't waste your time trying to hit it straight. Work with what you have, there's no doubt it is more consistent that a straight shot will every be.
So, how to do you shape the ball from left to right, or right to left. Personally, with my swing I know there are many things I can do to change the shape of the shot. Its just something I've learned from reading and practicing to see what works for me. I wanted to attach the video of the all time greatest player, Jack Nicklaus, demonstrating his one swing approach to changing the balls flight. It really simplifies the entire concept, and provides a great baseline.
It wouldn't be a stretch to imagine that Jack knows what he's talking about.