I want to reduce my tummy by simple ways.. help me

Try some sit-ups or stomach crunches... there should be resources on the web which tell you how to do these exercises.
:)
Hope this helps

Let me just say this first off, you can't target fat loss for one area, fat will be used as energy for your workouts and also be reduced after a time with cardio/reisitance training and a healthy diet, I'm not saying you have a lot of fat in your stomach area, but even a small layer will hide the muscles you have. That being said, To tone up and strengthen the muscles under fat in the stomach area here are some good ones; Crunches, Lie on couch or bench that allows your upper back to hang freely. Place your calves on the top of couch with your knees at a 90 degree angle. Place your hands and shoulders toward knees. Keep your back rounded a 2-4 inch travel, raise pelvis and round your back as you curl your torso up toward your knees, Hold 2-3 seconds, 15-25 reps. Also; stand with feet, shoulder width apart, knees slightly bent and arms across chest. Light contract abs, hold. Lower your upper body from hips to head down toward floor, aloowing spine to curl-Hold. Return to starting position, 15-20 reps work up to 3 sets 2--25 reps. Also try *hip lifts/roll, start with 10 each side work up to 20 3 reps. Squats/lunges 20 reps, 3 sets. For cardio, run, walk, swim or bike 20-30 minutes, work up to one hr. 4-5 times a week. Ellipiticals and glider or stepper machines are another good workout.