Valley fold and unfold both ways in half. Valley fold the sides to center so they overlap by approximately a millimeter. Valley fold and unfold. Turn the paper over so the color side is facing up. Valley fold to the creases made in step 3.
Valley fold the flap down.
The fold is just above the bottom edge. Valley fold the sides exactly to the center. Valley fold and unfold through all layers. Valley fold the corners to the sides to form the collar. These folds extend just down to the existing crease.