Mark the pocket opening on the right side of the garment with tailor’s chalk or a fabric marker pen. If your fabric is lightweight, fix a thin strip of iron on interfacing to the wrong side of the pocket opening on both sides of the seam allowances where the pocket will be stitched.
Lay the pocket bag right side down on the right side of the front of the garment. Taking a 1cm seam allowance, sew the pockets in place. Repeat the process, laying the pocket bag on the back of the garment.
Press the pocket bags and the seams away from the body of the garment, and under stitch the pockets to the seam allowance to prevent the pocket bags from rolling back.