Hi Julie,

To make the legs, divide the work identifying 2 stitches for
the front central space between the legs, 2 stitches for the
back and 18 stitches for each leg (you may find it useful to
use stitch markers). Join the last stitch for the leg on the back
side to the front side, working a single crochet stitch (this sc
will be the first stitch of the leg). Now the stitches of the first
leg are joined in the round. Continue working the first leg:
Rnd 21 – 46: sc in all 18 st [18]

Basically, you join the last stitch (where your crochet hook is) to the 23th stitch of the round, you then have a smaller round of 18 stitches, on which you continue crocheting Rnd 21-46 of the first leg.

I hope this helps!