After they cut out you just pull them off and this is what they look like.
Take the pieces and fold to shape the box.
Take a glue stick or glue of your choice. I used those little glue dots and glue together where the pieces fit. Then I took a sandwich bag and cut it and inserted it where the window box is. I'm sure there is something else you could use, but this is what I had...so I utilized it.
Here it is! That's a muffin...not a cupcake - but you get the idea. When I noticed that the picture was blurry...I had already eaten the muffin :-/
Happy Cupcake Boxing!