Prepare a piece of plain paper. Fold in half along the center line. Lift two corners and fold to the center line.

Turn the paper over. The vertices of the triangle are folded to the center line.

Fold both sides to the center line and press at a small angle.

Fold in half along the center line.

Lift both sides and fold them in half.

You're finished. (See the figure below for detailed methods. )