Thank you for replying.
Yes, I was instructed to 'top stitch the right shoulder seam'.
I am sorry, but I don't know what you mean by back stitches.
I have the two shoulders, on sewn, the other both pieces cast off, with 14 sts on a stitch holder front (middle, ie, the neck?) and 14sts on a stitch holder back, in the same place.
I don't know how to pick up the stitches that I have cast off, if that is what is being asked.
You may have guessed, complete beginner!