The best way to become a Nordic Walker is to walk with an instructor. Of course you can teach yourself by reading about the technique and watching videos, but then you're not able to observe yourself and errors might creep in.
With an instructor by your side you can be sure to get the technique right.
Here are a few points to remember when Nordic Walking:
keep a good posture
(stand tall, shoulders relaxed,
soft knees,
view to the horizon)
match the pole plant with the opposite heel strike
push backwards to propell yourself forwards
(give it a really good push)
open and close your hand at the right time (close when swinging forwards, gradually open when pushing backwards)
have one straight line from the shoulder joint to the tip of the pole at the end of the push
swing your arme from the shoulder joint, don't bend the elbow too much
plant the pole at an angle
(the pole is never vertical in front of you when you do Nordic Walking)
rotate your ribcage and hip in opposite directions
Does that sound like a lot?
Yes, it can be a bit overwhelming to start with. I always compare it to trying to ride a bicycle for the first time. You wouldn't expect to do that perfectly straight away but before long it's second nature.
So with time and a good instructor you will get there.