So, pretty simple really. Just paint your nails a base colour, once dry you can start dotting them with your nail art pen. I got mine from Primark for a bargain!
I would suggest practicing a little bit on paper before you try on your nails. I found that mine gave the perfect splodge of white by just pressing the tip of the pen down vertically for a second. You want to try to do them so they are all roughly the same size if you can. I can definitely see myself trying this design in lots of different colour ways. I have already tried grey and black which you can see in this post.