Holiday Tissue Toppersa Plastic Canvas Book by ANNIE'S ATTIC

It seems like almost all plastic canvas tissue cover patterns are for small square tissue boxes. When what most people buy rectangle boxes either regular or large size. I've heard you only need to add 2 threads for the larger boxes.

i have this kit and i don't know the first thing about how to do it. do you have a book or something on the computer that will help me. thank you