How can i i lose that thin layer of fat covering my abs?

Change how you eat: Lose fat, build the ab muscles. What needs to happen is that you change your attitude toward eating -- food is fuel, and being hungry much of the day is good for you. Get sufficient quality protein (1 gm/pound/day while you're building muscle is plenty) and micronutrients from a varied diet. Resistance training (cable pulls are one choice out of many) will help more than endless crunches.