Step 1: Cut the card into a square. It doesn't matter how large the square is, though the ornament is somewhat easier to make with a larger square. You can center the main image or not. I usually don't.
Step 4: Starting at one corner, make a 'paper airplane' fold. Unfold, then repeat for the three remaining corners.
Here's what your fold lines will look like when you are done with all the folds.
You can hang these ornaments from the tree, use them to decorate presents, or even place a small gift inside of one!