Is this a free online pattern that you should give us a link to? It might help us to help you better.
From what you've typed, though, it sounds like you are going to pick up the gusset stitches, just like you would if you were knitting a sock. There is a video on this site for picking up stitches, just scroll down till you see it. You might also check out Silver's Sock Tutorial for great info and pictures on how to pick up a sock gusset.