Look at the point of the ball where you want to hit the ball. If you want it to curve towards the goalie (in-swinging) , kick the ball on the right side and on the left side if you want the curve away from the goalie.
Take a running start. Aim for a bottom-right of ball (for an in-swinging ball). Place your planting foot (left foot if you kick with right) at a 45 degree angle towards the ball. You want to make contact on the ball with the "knob or ball" behind your big toe on the outside of your foot. When you perform the kick keep your ankle in the locked position and swing your hips with your kicking leg around your body so it goes over the opposite leg. If you want it to curve away from the goalie you'll need to hit the ball in the bottom left corner for a person kicking with their right foot.
Hi James & others, one additional point to Vincent's good explanation. Don't overkick. Most players try to kick the ball too hard. make good contact first. Try kicking at 75-80% of your max. It will keep your leg muscles relaxed and the ball will go farther and bend more.