It usually means clean colon. You don’t have to do anything. As soon as you start to take unnatural foods, stool will turn dark brown. If you are still not sure – take fresh natural yogurt or do yogurt enema.
White coloration is lack of bacteria and greenish is excess of the bile.
New born have yellow colored stool until they are feed unnatural food.
If you do complete intestinal wash – the first stool is most likely to be light yellow. The flush is more like complete wash, only longer and very little liquid. You can ask qualified yoga tutor for safety guidelines and correct procedure of complete wash.