I am fat how can i lose weight?

Slowly: Diet and exercise. Vegetables, fruit, protein - fish, poultry (chicken, turkey) - little red meat. Avoid sugar and starch (bread, potatoes, pasta, rice, ) as much as possible. Eat 3-5x/day. Daily moderate exercise, but not so much that you "burn out" in enthusiasm or hurt. Lots of water. Go slowly. Adjust for gradual, but definite weight loss over the long run. That way you will have good habits.

Overall weight loss: With natural weight loss (by eating fewer calories and exercising more to use up stored fat), one loses fat from all body parts. It is hard to just lose the waist or the belly. Doing exercises to strengthen and build up the abdominal muscles can hold the tummy in better, which will improve the appearance of the tummy. Be sure to avoid sugar and simple starches (simple carbs).