This one looks trickier than it actually is. But I hope the photos serve as a good guide.
For the collar view only sew one yoke to the back body with right sides together.
1) Sew the front and back shoulder seams together.
2) Take your remaining yoke piece and with right sides together, join it to the front facing shoulder seams.
*Once sewn together it will look like this.
3) Grab your collar pieces and sew all place then with right sides together. Sew the sides and around the top. Turn right side out.
4) Position the collar around the neckline and baste to the body.
5) For the next step you are basically joining the facing to the main body, in a way. Fold the shoulder extension and yoke to match to the body neckline with right sides together. This will include the collar sandwiched between the two layers. Stitch all around.
6) Turn right side out and spend a good amount of pressing around the neckline seam to ensure it will lay flat.
7) Turn the edge of the yoke facing under 3/8" (1cm) and overlap the body yoke seam slightly. Topstitch through all layers to secure.