Facing cut with the pattern up, unfold it and place now interface on the wrong side of the fabric. You must decide which interface to place according to the weight of the fabric,interface should enhance the fabric but not to make it rigid.
You get this with facing unfolded ...
Now, overlock around the bottom edge of facing .... if you don´t use overlock, to"cleanse" the edge of the facing with bias tape.
Ok, girl ... comes the fun .... put the facing on dress, the sides "good" of the fabrics found each other, start by placing the center of facing above the front neck line and place pins from the center to the sides, remember that shoulders of your dress are ripped and separated.
Then place pins in facing starting from the center of the armhole (side seam of the dress) to the shoulders and finally from the center of the rack (back) to the shoulders. If you followed all the steps correctly, facing fits over the dress perfectly.
Sew around the neckline, armholes line and back line, leaving a centimeter seam allowance, however, consider a couple of additional caveats ...
Sew along these lines and finish the seam one centimeter and half before the shoulder seam, the seam of the shoulder where it joins the front shoulder with the shoulder back. The image shows up where it should be you sewed the seam lines on the neck and armholes.
The back seam line should be up to two centimeters before the zipper. Observe the image.
So far the first part of this tutorial, if you have questions or need to understand something, you know ... shout!
I will try to help resolve all your doubts.
The next tuto will be to solve the finish of the back in facing with the zipper.