Next I was to open the zipper and lay the zipper face down on the right side of the fabric with the zipper teeth to the outside of the seam line. Before I could do that step I'd need to baste the seam line onto the fabric. Note to self: This would be much easier to accomplish before sewing that back seam.
Now for the fun part. Use your zipper foot to sew a 3/8" seam. Take your time. It's not a race. You don't want to have to rip this out.
Repeat for the left side of the zipper. Remove your basting stitches, place the dress on the mannequin and enjoy your handiwork. And don't forget to breath. All that's left are the lining and hems. You can do it!