What are the best abs excersises to do ? and sets should i do ?

Understand why: Several times a day, "burn" your ab muscles with heavy resistance (consider cable pulls as in the photo) and alternate with many reps (crunches are easiest on the back). Stretch first especially for your back. Since you're developing these, diet / do cardio for definition; a man needs no body fat, a woman needs little. Best wishes.

Abs: For flatter abdomen eat healthy & get physically active. Calories burned > calories consumed. To tighten ab's: crunches, reverse crunches, exercise ball crunches, pelvic thrusts, lying leg raises, side bridge & “bicycling” exercise on back. Engage in regular aerobic exercise (i.e. running, swimming, Nordic track, bicycling, kickboxing, walking, cross country skiing, hiking, etc.)