Putting a zipper into a dress is a technique that requires a bit of precision in order for the dress to look good and the zipper to operate smoothly. The zipper must be centered exactly over the back seam of the dress, with stitching that is evenly spaced on both sides. Sewing it in without careful preparation will likely result in a zipper that peeks out from gaps on the back of the dress, or one that snags on stitches that are sewn too closely to the zipper’s teeth.
Baste close the seam where the zipper will be placed. You can do this either by hand or machine, using long running stitches. Do not make these stitches too small or tight, as they will later be removed.
Using a hand needle and thread, use long running stitches to baste the zipper in place. Remove the pins.
With a seam ripper, remove the basting stitches holding the zipper in place and the basting stitches keeping the seam closed.