Casting on in the middle of a project?

I just taught myself to knit last month so I’m still a relative newbie. I’m trying to make this Bunny Buddy Blanket from Lion Brand http://cache.lionbrand.com/patterns/50722.html but I’ve come across a snag.

At the end of row 39 I have 40 stitches on my needle. Then for rows 40 & 41 it tells me to cast on 12 stitches & knit across. If I cast on 12 stitches, that leaves me with 52 stitches on the left needle. Am I supposed to cast them on and then knit across them?

Am I making these two lines of the pattern more confusing and complicated than they really are?

TIA!

I find it difficult to figure out how to cast on stitches at the beginning of a row and not have some huge gap, so I always cast on at the end of the row and then knit across them and the old stitches to cast on at the other end. Works just fine!

How do I cast on at the end?

You can do either Cable Cast On or Backward Loop. There are videos in the Basic Techniques section for cast ons.

Thank you!