Here's what your printout will look like.

Start by folding it in half lengthwise (hot-dog style if you’re in elementary school!)

Unfold and refold width-wise (hamburger style).

Unfold again and fold the short edges in so that they meet in the middle.

You should now have a sheet divided into 8 equal sections.

Fold hamburger-style again and cut a slit from the folded edge to the next folded line.

This is what it will look like.

Continue to pop out the resulting diamond shape by pushing the corners with attached sections towards each other until it forms an X or cross shape.

Finally, fold the sections so that the cover is facing front.