A mizou is just basically a soul grind variation where your soul foot is in front and your back foot is trailing in the backside position. To learn how to do this trick, find the curb or low rail you are going to grind. Stall in the Mizuo position on the curb and get the feel for it. If it does not feel natural or it feels really weird, try facing the other direction and figure out which direction is your natural side. Then try jumping up onto the curb or rail and holding that position. After you can do that for about thirty seconds, try coming at the curb or rail with a little more speed than you would have if you were soul grinding. Jump on in the mizou position and try grinding. This trick probably won't come to you on your first try, but if you keep trying it you will get it.