Tips on to lose weight..

I want to lose weight so I can be more helthy and confident. I'm not picky in eating, I drink water and I now only eat 1 plate of food and at times I will eat half a plate when i go out to eat. I would love to know what are some tips on loaing weight. I'm on the border line obese; 5'6 and a half and I weigh 175 lbs. My goal is to lose 20 pounds by Christmas and another 20 by prom. I just not that modivated; <--- sorry for spelling the word wrong...possibly.