Working on D. Bliss A Line Coat from The Big Easy Book. Buttonhole Row 1 reads: P to last 7 stitches, P2tog,y2rn, p2tog,k3 (wrong side). Row 2: K3,p1,p into front and back of y2rn, p to end. How do you p into front and back of y2rn? Have tried several times and can't figure it out. Thank you.