It is probably pretty common for a woman to store excess fat in the stomach area. This just seems to be a very common area for most women and this can cause a woman to look heavier than they really are. Although it isn't possible to burn the fat on in just one particular area of the body, you can lose weight overall to reduce the stored fat on the stomach and to help increase the muscles in this area as well.
First you should go ahead and calculate your BMR or basal Metabolic Rate. This is the amount of calories that your body actually needs on a daily basis to be able to work properly at it's state of rest. So if you exercise while providing your body with it's BMR requirements you are going to help burn off more calories than you eat daily. This is the formula for your BMR.
655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years) = BMR
You should count your calories and then eat within the numbers to lose the weight and get to where your muscles will begin to show.
You should also make sure that you take a daily multivitamin and one that is going to help your body be able to support more muscle mass and fat loss. Your multivitamin needs to regulate your body by giving it the nutrients you might not be giving it with your diet.
You also will need to start some abdominal routine that should be performed about three to five times a week. This should probably have three to five different exercises that you can do. You should probably try to do three to four sets of ten to twelve reps of each of your exercises. Some good examples of exercises would be: