You need to not eat junk food and you need to do a combination of cardiovascular exercise and weight bearing exercise. No amount of sit ups will ever help ge rid of actual stomach fat.
Try one of those electic toning machine things that you strap on and it tenses your muscles for you, this will tone up problem areas but there's no way to target specific zones to lose fat, you need to lose it all over.
Maybe try an inch-loss wrap as well? And skin firming cream?