Draw round the pattern on a sheet of smooth paper (stick to the dimensions given). If you want a stiffer pouch with a custom inside, you can glue a sheet of fancy paper to the white side of the smooth paper.
Cut out the transferred shape.
Draw the fold lines using a ruler.
Fold the sides over first.
Then fold the top and bottom.
Fit a paper fastener where the side and bottom flaps overlap to keep the folds in place.