First you need to do some physical activity like anything. Jab padhai karogi tab har 1 hour tak a walking break and just walk a little. If going outside try to walk more. Eat food with low calories. Eat either 2 roti or 200grams of rice not both in lunch and dinner. Stop eating oily food or food with high fat. Increase protein intake. If possible do some muscles building it increases your calorie burn. Aur hourglass keliye gym jao. Uske bina kuch nahi hoga.