Odds are your first time, if not your first couple times, the fry will not make it. You see, the thing with betta fry is that they are SO delicate and very sensitive to changes. As for food, I agree what they all said so far. Have you considered getting some IAL (Indian Almond Leaf) ? it will stain the water but it creates the most ideal conditions for breeding, and betters in general. They are found where many bettas come from and they are usually widely throughout asia with betta breeders.