How do I knit this in order to transfer from double pointed needles to the circular needles?
Assuming you’re right-handed: You have that circular needle with 6 stitches that you’ve cast on in your right hand; the live end of the yarn will be on the leftmost stitch. Take the dpn with the ear flap stitches in your left hand. Now knit the stitches from the dpn onto the circular needle just as if you were knitting them from the left to the right when you were creating the earflap. Now the circular needle will have 6 stitches and then the earflap. I’m guessing that the next thing it will have you do is make a bunch of stitches to get you around to the other side of the hat, then knit in the other earflap, then maybe make a few more stitches before you join everything up to knit in the round.