Kitten formula works, so does goat's milk (for most orphaned animals, actually). If you don't have an eye dropper, you can make a q-tip very wet and dribble it in, but be careful it doesn't catch any of the fluff in it's mouth. Do not use cow's milk. Try not to feed it on its back like you would a baby, but rather tummy town. They tend to aspirate if you do it the other way. It is probably almost old enough to drink from a small animal bottle. Since the eyes are almost open it should be urinating/defecating on its own, but if you don't see signs of this, massage its bottom with a warm damp rag.