Good way to loose weight ? and is water good for loosing weight hot or cold?im 18, 5 foot 2 n 10stone am i fat?

how does water help ? how much to take ? hot or cold water? .. and how much walking or stuff should i do? Also am i to big for my heath im around 5 foot 2 , 18 year old girl and ten stone maybe ten 4 or 5 at times