mark the length of the buttonhole beginning and the end, make sure the length will be big enough for the button to go through. use a zigzaw stitch shorten stitches sew on one side then sew side by side next row. then lenghten stitch and bar tac on each end. Try on scrap first and cut hole and make sure your button will go through hole. then when you get it the right size. then do it one your project.