Okay, it is easy to do, but not so easy to explain.
Hold niddy noddy in your left hand. The top of the niddy noddy should form a "T" with the middle section as it faces you. Rotate the bottom part of the niddy noddy 90 degrees. (The tip of the bottom piece should be facing you). Now, holding the niddy noddy at the bottom, start your yarn at the bottom and bring it up and over the top left hand bar of the niddy noddy. Now your yarn will be at the back of the niddy noddy - bring it down and around the bottom of the rear lower piece - now up to the right hand bar and bring it across the top to the front again - down the front and around the bottom of the front lower piece. (One complete round) Then repeat again.
This is probably as clear as mud... :??