Welcome to the forum, Kay!
Which pattern are you working? If the construction is something like the booga bag, you'll have one row of stitches that you've worked, and you'll then proceed around the rest of the bag, picking up stitches so that you have live stitches all the way around. Keep using your circ since you'll be knitting the stitches on it. If you find actually picking up the stitches is tricky, try using a crochet hook or a smaller needle to get the yarn through; then put the stitch on the circ and head to the next stitch. And yes, once you've picked up all the stitches, just begin knitting in the round.
I hope that helps!