Losing abdominal fat is notoriously difficult to do -- but it can be done.
The first thing to realize is that you typically can't target fat loss in the belly, without also losing fat across the entire body. In fact, the human body is programmed by centuries of evolution and adaptation to store body fat in the torso. It's typically one of the first places people put body fat on, and one of the last places you'll lose it.
The best method of losing a fat gut is a combination of exercise and improvements to your diet. Eating the right amount of calories to lose weight is also critical. No matter how healthy you eat, if you are consuming more calories than your body is burning, you won't make a dent in that belly.
In terms of exercise, a combination of cardio and weight/resistance training is ideal. You can perform crunches if you want, but ab exercises alone will NOT cause you to lose excess stomach fat. The most crunches will do is help develop your core and help you get better ab muscles that will eventually show once you've lost the belly fat.
In terms of diet, you first want to clean out all the junk you are eating (soda, fast food, excessive sugar, etc.) and then start to transition to a clean eating regimen -- which simply means consuming whole foods that aren't processed. That includes complex carbohydrates, some healthy fats and plenty of lean protein.
Here are a couple of links to get you started, with much more detail than I can provide here in Yedda (that's why I created them):
Best of luck!
