How do you ski backwards?

You weave in and out of a series of 5 feet tall gates inside the ground along a defined course. If you skip a gate you DNF "did not finish". The faster you complete the course the better. It is important to hit the gates every time you go for the gate...the correct gear will prevent you from getting hurt. If you find yourself not hitting the gate make your turns closer to the gate then once they are close enough to hit them, put you pole guard (hand) in-front of yourself to push the gate away. This is a good strategy but not needed.

You also have Giant Slalom, Super G (Super Giant Slalom) and Downhill. These are faster variations of the traditional slalom. The course is longer and the flags are positioned further apart. This makes the course faster as you need to make less of a sharp curve to reach the next flag. Downhill being the fastest.

In case you are talking about waterskiing, slalom is the same as in snow but with boueys floating on the water.

they go in between gates and they if they miss one there is a penalty