You need to do some good cardio and strength training exercises. Both help to burn fat. Try doing a 30 minute jog (or strenuous swimming, if that is the exercise you are comfortable with) 3-5 times a week, and also add some good strength training 3-4 times per week. Strength training will help you to build muscle, which actually makes your body burn more fat while at rest. Abdominal exercises you can do every day, but if you are working any other muscle group (arms, legs, etc) than you have to give your muscles a day of rest. Best of luck to you!