How to fold letters

The specific operation steps are as follows:

1. Take a square piece of paper and fold it in half.

2. After folding in half, fold the paper below by one third.

3. Fold a triangle at the two corners of the bottom.

4. Fold inward along the vertical side of the small triangle, and fold both sides like this.

5. Take the folded vertical line as the boundary and fold the upper two corners into a triangle.

6. Fold down the corner folded above in the horizontal direction, so that the paper at the bottom is just covered.

7. Put the folded part into the gap below. So an envelope was folded.