Back piece is left unaltered. Cut the front piece along the center line and from dart apex to the center of the leg cuff. Experiment with different widths of the pleats. I suggest that you start with the amount in the picture. The picture speaks for itself, I hope.
Pleats are optional.
Bermudas can be sewn also with ordinary darts. Cut the back piece of the basic pants as illustrated in the picture. 4 cm from the waist at the side seam and 7 cm from waist at the center back seam. Draw the pocket mouth and the pocket on the front piece. Copy the pocket beside the front piece and cut it from the dart apex vertically across the bottom of the pocket.