Help me out with the joining of the cowl

My CO is the provisional cast on, 31 sts cables top and bottom of the cowl in the middle is the Fisherman’s Rib. How do I join it?
BTW I’m doing this flat knitting.

Can you give us the name of the pattern and a link if possible? Don’t post the pattern itself just a link.

The first 18 sts cable left (3/3L) 9 sts Fisherman’s Rib the last 18 sts cable right (3/3R) cast on 33 sts, then I added 12 more sts. The 31 CO I goofed on the pattern so I :frog: it. It’s for a BBE (Brown Bag Exchange) .