The ingredients are deceptively simple -- masa de harina (corn flour), water, and salt. Masa itself is corn that has been treated with lime and water (not the fruit, like, chemical lime) then washed (lime is totally not edible) and ground into a flour -- you can't substitute starch or meal for it (look near the tortillas/salsa section for it, or barring that the ethnic foods section).
To actually mix the dough, the flour itself will probably have the ratio you are supposed to use on the bag -- it's going to wind up being like a 2:1 flour/water ratio (again, consult the bag or google it). Also it uses salt, nearly forgot (like a pinch, like all doughs).
