This a good example of "perfect binding," where the pages are stacked and one edge is glued with a special glue called a padding compound. In this kind of binding, it is crucial that the edge being glued is cut perfectly straight and very clean. Once the pad was glued, I simply printed the design onto cardstock, cut it to fit, folded it over the top, down over the back and up over the back bottom edge, then glued it to the chipboard backing the notepad. Done!
Simple, clean, handy. If I was in production mode, I could turn out a dozen or more of these in an hour.