Well like Mike said your diet is really going to determine whether or not your abs will be visible. Along with that yes you will need to build your ab muscles. Ab Rollouts are pretty great for building muscle. I would start doing exercises that involve some power lifting though. It will increase your strength like crazy I started with 5x5 Stronglifts in the beginning and it really helped me, this will also help increase core strength.
As for your diet, I'm not expert but, you;re young so just improving your overall nutrition while working out will essentially get you where you want to be without the need for counting calories. I believe the average recommendation for calorie intake is about 14 cals per pound of body weight to lose weight. I know you work in KG but Im just going to use pounds for now. Many people recommend about 0.7-1.0 grams of protein per pound of body weight, along with that 20-25% of your calories should come from fat, and the rest of your calories should come from carbs. Get most of your protein and carbs from lean meats and veggies and you will be good to go. If you have any other questions message me.
