You don't lose 'stomach fat'. There is nothing other than liposuction which can remove fat from only your stomach or from your stomach 'first'. Fat is lost in the reverse order in which is was put on.
Exercise is not as important as changing your diet. Get rid of the sugars, fried foods, fast foods and junk foods and you will have done more than having spent an hour a day on the treadmill. It's all about taking in LESS calories than you BURN each day. And exercise (unless you really do a crapload of it) doesn't burn more than you burn by simply being alive and walking around your own house, breathing, beating your heart, pumping your blood, etc.
It's your diet.
All the other exercise stuff will make your muscles look better when you have lost enough fat for anybody to see those muscles. And exercise is good for you in general and building up muscles actually CAN increase your metabolism which will burn calories faster but doing sit ups or anything else doesn't 'target' one area. That is a huge myth and everybody except for the informercial industry will tell you this singular truth.
You simple have to eat LESS. And/or eat BETTER. But exercise is a great thing and it can create endorphins which can improve your mood as well as cure things like 'depression' or 'moodiness' and helps combat PMS and other disorders.
But unfortunately, you will lose fat everywhere proportionately and not just on the spot you exercise. Sorry. It's not a reason to stop exercising though. Create targets and goals and look forward to achieving whatever they are through exercise. Even the junk from infomercials will help you out IF YOU ACTUALLY USE IT but that is the only thing about them that is worthwhile. You might be just as well off using household furniture but....don't let that get you down. Just do the exercising anyways.