Three needle bind-off is used to join two separate pieces of knitting...have you done it before or watched the video? (it's the last video at the bottom of this page: http://www.knittinghelp.com/videos/casting-off
From what I can tell, you are connecting the front and back via three needle bind-off (the shoulder seams). So, say, the first 15 of the front and last 15 of the back would become the right shoulder, and the 15 + 15 at the other end will be the left shoulder seam. Then the middle 30 (or 36 in your case) from each piece will be knit in the round to make the turtleneck. When you finish this part, there will be no live stitches left.
As far as the finishing goes, you're knitting the sleeves flat. So you'll need to sew the shoulder edge first (perpendicular to the shoulder seam that you three-needle-bound-off) then sew the actual sleeve seam, starting at the wrist edge, and ending 5" from the shoulder edge, if that makes any sense.
It's kind of an oddly written pattern, but I get it now that I've taken a good look at it. LMK if I made any sense! :D