The first step in sewing together a pair of jeans is to sew down the patch pockets in back. You just cut out the shape of a pocket, leaving your standard seam allowance on the sides and bottom and double allowance on top. Fold the top of the pocket over twice, press, and sew down. Fold over the sides and edges and press. Pin the pockets to the back of the pants, being careful to line them up so the two sides are symmetric. Sew along the edges.