Need your HELP on weight loss?

So i weigh almost 9 stones and think its time i started doing something about it as my bmi is around 29, im thinking of eating healthier - eg more veg,eat more regularly but smaller portions, cut down on the caffeine and drink more water, and do about 30mins of walking a day on the stepper how long will it take me to lose a stone? .. and will my face go skinnier or what will be the first part of the body i will lose weight from? Also as i will do a lot of walking will my backside appear larger?