What should be done to get rid of the flabs in my stomach?

More muscle less fat: Even the most toned abdominal muscles will not reveal the abdomen you want if they are buried under a beer gut. Decreasing body fat is a key component of washboard abs. That said, anything that strengthens your core (sit ups, crunches, leg lifts, torsion, etc ) all play a role in building those muscles.

AB Flat: You need to lose weight in general & a certain % will be abdominal fat. Eat healthfully & be physically active. Calories burned must > calories consumed. To tighten ab's do crunches, reverse crunches, exercise ball crunches, pelvic thrusts, lying leg raises, side bridge & “bicycling” exercise on your back. Engage in regular aerobic exercise.