I’m assuming your question is about the directions to join the raglan seams and pick up sts around the neck? Join 3 of the seams leaving the left back raglan seam open until you’ve finished the neckband. Then starting at the left sleeve top, follow the directions for your size. Once you’ve picked up all the sts,including the sts knit from the front holder, cast off all sts. You’re just finishing off the edge so you have a nice continuous band.
Here’s a video for picking up sts in case you need one.