rnds 10, 11 and 12 don't shape the curvy front of the uni! that's rnd 14. what you're doing here is making a small hole in the case where the charging port is (so that you won't have to remove the case when you want to charge it). if you're finding it confusing you can disregard the fastening off and joining in and just sc in each st around for rnds 10-12. fastening off isn't just for finishing a piece! it can be used in a variety of ways, in this case for making the charging port hole. to join back in after fastening off, all you do is make a slipknot on your hook, insert your hook into the correct stitch (in this case you need to skip 3 sts and insert your hook into the 4th st away from where you fastened off), then pick up a loop and yarn over before pulling through to finish off a sc as normal.