Well, to be honest the questions about which exercises work the best to get a ripped stomach are where you are going wrong.
Everyone has a six pack naturally, just like everyone is pretty lean. The only problem is that there is a layer of fat on top of all that lean muscle. The stomach is no different, in fact for men it's worse. Men store their fat on their stomachs while women mostly store it in their hips, thighs and butt.
So what do you need to do to get a 6 pack?
Well the first thing you need to do is lose some weight. Most people have a few pounds they can drop. If you really want a six pack but don't want to look like a marathon runner without any muscle mass anywhere you have to control your diet.
Okay, so whether you are a man or a woman if you are lifting weights you need to make sure that you are getting enough protein. You don't need to eat as much as a bodybuilder because they often eat too much, but you have to get some protein immediately after a workout. Using a protein drink will do the trick.
Everyone's body reacts differently to fats and carbs. You need to figure out which one makes you put on weight. I could never cut out carbs from my diet, so I cut fat way down when I want to get lean. By way down, I mean eating less than 10 grams of fat a day. Maybe you can stand to cut carbs and you can eat less carbs to lose weight. But you should always consume more carbs than fat and protein. Your body needs carbs! Never cut them completely out of your diet. Carbs = Energy. I don't have time to go over the biochemistry of it but your body uses carbs for energy easier than any other substance.