What should be my exact weight?

i weigh 104 kgs that is 228.8 lbs and my height is 5'6 that is 167cms....i am starting walking tomorrow and we have decided 1 hour will be good..how many hours should i walk to lose weight fast and plzz recommend some ab exercises which will be effective...and how many times a day should i drink green tea...my friends said 4-5 times but i think thats just too much..plzz reply