4 - Matching notches, pin the right side of the pocket lining and pocket detail to the right side of the pant front with the pocket detail sandwiched in the middle. (Make sure that you are sewing it to the pocket curve and not the crotch curve of the pant front. This curve is not notched.) With the pocket lining on top, stitch all layers together along the small curved edge. (You can use your basting stitch as a guide. - This really helps to keep the pocket detail an even width.) Trim seam allowance to avoid bulk. ( I trim the seam allowance for the pant front and pocket lining to 1/8" and one of the pocket detail seam allowances to 1/4". This will make it so you don't see a line on the outside of your pant where the seam allowance ends.)
5 - Flip the pocket lining around so that it is wrong sides together with the pant front. Match notches. Press the pant front and pocket lining towards seam allowance with the pocket detail standing up between them. (If your basting stitch is showing anywhere pull it out now.)
6 - Pin the right side of the main pocket to the right side of the pocket lining along the long edge. Making sure that the pant front stays out of the way, stitch the two pocket pieces together (only along the outside edge).
7 - Match notches of the pocket pieces to the pant front and baste along the top and side through all layers.
8 - Trim the pocket detail if necessary so that the ends are flush with the pant and pocket.