This is the simplest and most versatile way to apply a zipper. It is easiest to apply early in the project, when the fabric can be opened out flat.
1. Finish the raw edges of the fabric by zigzagging them separately. Pin one edge to the other, right sides together and raw edges even. Lay the zipper along the pinned edges in the position required—such as centered between the top and bottom of the seam, or at one end. Mark on the seam allowances the top and bottom of the zipper—just above the zipper pull at the top and just below the zipper stay at the bottom.
2. Set the zipper aside and stitch a seam of the specified width as far as the first mark. Backstitch two or three stitches, then machine baste along the seam line as far as the other mark. Begin stitching with a normal stitch length again at this mark, and after a few stitches, backstitch two or three stitches, then continue stitching to the end. Press the seam open.
3. Place the closed zipper face down over the seam allowances, matching the top and bottom of the zipper to your markings and ensuring that the teeth line up with the seam line; pin. Hand baste all around the zipper through all layers. Remove the pins. Turn the fabric over and use pins or a water-soluble marker to mark the top and bottom of the zipper (as in step 1) on the right side.
4. With a zipper foot and working from the right side of the fabric, start at the top mark and stitch ¼ in (5mm) from the opening edge. When you reach the bottom marking, stop with the needle in the fabric, raise the presser foot, pivot, and stitch across the bottom of the zipper just below the stay. When you get ¼ in (5mm) beyond the opening edge, pivot again and stitch ¼ in (5mm) from the opening edge. When you are back to the top mark, stop with the needle in, raise the presser foot, and open the zipper just enough to get the zipper pull out of the way. Repeat the pivoting procedure, and stitch across the top to your starting point.
5. Instead of backstitching, which is too noticeable when topstitching, leave long ends of thread at the beginning and end, and use a pin to pull the top threads through to the wrong side, then tie them and the bobbin threads together, and trim off the ends. Remove the hand basting, and use a seam ripper to remove the machine basting along the seam line over the zipper.
Now you've mastered the basics, why not learn some more techniques, or try some projects from Stylish Home Sewing by Torie Jayne.