I need help with my weight?

Ok so my names C I'm 15 I weight about 57-59 kgs Im not sure what my height is but people say im tall :S and I've been wanting to lose weight on my arms, stomach & thighs so I was thinking about doing laps in my pool and eating healthy but I was just wondering how much time would I need to spend doing laps and how many weeks would I need to do, to lose about 8-10 kgs?