It's really super simple. follow your pattern until you get to the point where you are going to attach the collar (or in this case hood) and yoke facings...the pattern will probably call for you to baste the collar to the shirt then add the yoke facings but as you will see I am super lazy and just pin it all then sew it all at once, but it's of course probably best to baste...I just don't.
So here's where we are in the pattern about. You've just attached the hood or collar and now you are supposed to sew on the yoke facings.
I am using double fold bias tape because that's all I had but it looks better with the single fold stuff plus you don't have to iron it open first. Anyhow, you need a length about an inch longer that the space between your yoke facings or if there aren't any, your collar. Press about 1/4" under.
Lift up your yoke facing and open one of the folded sides of the bias tape. Then, pin it right side down (on the collar/hood....NOT on the shirt side) about a 1/4" under the yoke facing. You will want the crease of the fold to be about where you will be stitching.
Trim the bias tape (if needed) about 1/2" past the other yoke facing.
Then, fold that end over 1/4" lay the facing over it and pin.
It should look like this.
Stitch and trim the seam allowance.
Flip the bias tape over so the wrong side of the bias tape is facing the wrong side of the shirt. Pin it down and edgestitch the bottom. I didn't think to take a pic, but the facing should be even with the shoulder seam...see how it's overlaping in this pic make sure it's right before you stitch the the bias tape down.
Oh! Look you can see how the facings line up in this pic.
And that's it your done! If you want and even more professional/storebought look you can edgestitch the top too, but like I said I was in a hurry so I didn't.