Via Sewing.org via Coats & Clark's Sewing Book A to Z
This is hands-down the most useful tutorial I have ever seen for the invisible zipper. Nothing is worse than sewing a zipper on wrong and this is very useful to preventing that.
Attach the invisible zipper foot to the machine, with the needle lined up with center mark. Place open zipper face-down on right side of fabric as shown. Pin in place with coil on seam line (5/8" in) and top stop ¾" below raw edge of garment (1a). With right-hand groove of foot over coil, stitch zipper until the foot hits the slider (remove pins as you come to them.) Back-tack.
To attach the other half of the zipper, pin tape face-down with coil on seam line (5/8" in) and top stop ¾" below raw edge of garment, as before. Make sure that the zipper is not twisted at the bottom. Use the left-hand groove of foot, making sure that the center marking is still lined up with the needle and stitch, as before.
Close zipper. Slide zipper foot to the left so that needle is in the outer notch. Pin the seam together below zipper opening. Fold end of zipper out of the way and lower the needle by hand slightly above and to the left of the last stitch. Stitch seam for about 2", as shown. Pull thread through to one side and tie. Change to regular presser foot and complete the seam.At zipper end, stitch about 1" of each zipper tape to seam allowance only.