Help with neck/shoulder shaping instructions

[Noia]

I'm making my first sweater and have come to the difficult part for a noobie, the dreaded shoulder/neck shaping! The instructions seem like they should be super simple but it's not clicking for me.


Shaping back neck:

Next row (RS): Patt 36 sts and turn, leaving remaining stitches on a holder. Work each side separately. Cast off 4 sts at beg of next row.

Shape shoulder:

Leave rem 32 sts on a holder. With RS facing, rejoin yarn to rem sts, cast off center 41 sts, patt to end. Complete to match first side, reversing the shaping.



I'm good with it till the cast off four part! Then my mind just shuts down on me! lol Do I cut the yarn? If so then where do I go from there? Thanks so much for any help!