I used to make these without a pattern when I was a teenager. Buy a pants pattern (elastic waist pattern works best) that is your size, when you put the front and back pieces on the fabric, make sure the grain is straight but place them so the crotch part is as close to the selvedge edges as you can, and do not cut the outside leg seam area out. Extend the top edge and hem edge to the fold and cut out. You now have two huge leg pieces. Sew the two crotch seams, then the leg seams. Now, just fold a pleat about three inches from the front and back seams, about one inch deep (outside of pleat should open to the side not center) sew the pleat down for about five inches on both front and back pieces. Make casing for elastic on top, insert elastic. Hem bottom edge. Done. The pleat is not a pressed pleat, it is a modesty pleat so that the pants do not cling to and show off "lady parts" as grandma called them.