Double poling is not just for Classic Skiing. When skating, you can double pole at the top of a hill to go faster down the hill, and you can use double poling in flat sections if your legs need a little rest.
Double poling should be a part of every workout and practice. It is a good way to strengthen your abdominal muscles. Strong abs are important in both skating and classic skiing.
This guy is an animal double poling! Usually as beginners, we take it a little bit easier, but make sure you do a crunch with your abs, bending at the waist.