We have some of our own how-to videos here but I am a huge fan of viewing any video that gets you learning as fast as possible. The video below by Marko Kantaneva has some great easy to understand video and some fascinating animations (on left) showing which muscles are working when. He also boils it down to 3 steps for first timers which include:
Step #1: Drag the poles with your arms straight down at your side
Step #2: Pick up your pace, allow your arms to swing naturally
Step #3: Start to grip the pole and apply pressure down on the strap
Now check out the video below...