HELP! p3 cast on?

I’m in the middle of knitting a dog sweater and I’m stuck on the arm holes. I have done the first part… but it then says,
-p3, cast on 6 sts, p to bind off sts, cast on 6 sts, p3

Please break it down step by step I’am a beginner please be as specific as possible!!!
Thank You :slight_smile:

Attached is the patter.
http://www.moonarts.com/blog/free_patterns/pages/pup-sweater-print.htm

Purl 3 sts, then cast on 6, purl around to the next set of bound off sts, cast on 6 more, and finish with purl 3.

To cast on sts, put the right needle into your left hand, use the knit or cable cast on, then swap it back to your right hand.

Thanks… but
How do i cast on mid row?

How do i p the next set…and meaning the next set of what???
Thanks So much!

I explained above how to cast on. Put the right needle which has the working yarn into your left hand. Use the knit or cable cast on, then switch the needle back to the right to continue knitting, or purling. You should have more bound off sts, that’s where you’ll work to, then cast on another 6 sts.