Those girls train very hard for a long time to achieve low percentages of bodyfat in conjunction with highly developed abdominal muscles. Unless you put in comparable amounts of work you won't look like that. To have a "toned" look is to have low bodyfat and a decently developed musculature, so if you want to be toned eat less, do more cardio and incorporate some resistance training into your routine. Specific ab exercises won't count for much untill you get to a low percentage of bodyfat (<12%).