It's just a quick thing to crochet.
I made a long chain with chainless double crochet foundation stitch. See the video tutorial here that I used to figure it out last year when making these skirts for the girls.
I then did 2 more rows of double crochet.
Finally I did a ruffle stitch around the scarf. You double crochet in the stitch, chain one and then another double crochet in the same stitch, chain one. Repeat in all the stitches around the scarf. (You can read better instructions in the pattern linked above for the skirts).
Like I said not hard but it looks cute.
And theses are the skirts I made for the girls.