Thumb gusset

I am knitting some Wristers from the Creative Knitting magazine. Instead of using 5 double needles I am using 2 circulars. On the Beg Thumb gusset I am a little confused on the following instructions: Working thumb gusset sts as knit sts, continue in established rib pat around… What does {working thumb gusset sts as knit sts) mean??? Thank you

It sounds like they are beginning to give you the instructions for how to make the thumb gusset there somewhere. They want you to make the stitches they designate for the gusset in knit only (knit every row will make St st in the round), and they want you to keep the rest of the stitches in the same rib pattern you had going for the cuff. If they don’t tell you which stitches become the gusset, I’m not sure what to tell you.