Well to put it as simple as possible, you can't.
Despite how may crunches you do, or leg raiser, you will not be capable to target the fat in your stomach. The reason being, you can NOT localize fat removal. Doing sit ups and crunches only work the stomach muscles and have completely no effect on the fat burned in that area.
When your body burns fat, it uses fat stores from where it can find fat. When you lose fat, your body will do so in it's own natural "balance.".
The best way to lose that ugly fat is through diet. There is no hidden secret, magic pill, or piece of equipment that will quickly remove any fat.
