I know looks at so important at your age so I'll help with some tips. You cannot loose fat from a specific area, it is lost from all over your body. So excercising a specific area where you want to burn fat doesn't make much difference but of course it will improve muscle fitness. The main area for you to start on is the food you eat. Simply put, small portions, eat chicken breast eggs, fish, eggs, salad, vegetables and fruit. No sauces or dressings unless you know what exactly is in them. Keep your carb intake very low, one portion a day is enough but you can avoid it alltogether. (Rice, pasta, Potato).
Running and cycling will be good excercise for you, cardio workouts such as Zumba, spinning etc are also good. Don't worry about strength exercises for your legs, you use them for the cardio so don't over tire the muscle on other things as it will inhibit your ability to keep up the cardio for long durations. Also you don't want to over bulk the thigh muscles and it will be counter-productive in your goal of attaining 'a thigh gap'.
Changing your body shape takes time, you should start to see noticable results after 6 weeks. Don't get despondant, just keep up the clean eating and exercise and you will get the result you want. If you feel feint or dizzy at any time, rest and eat. Remember if you excercise hard you need to take rest days. Look after yourself and stay healthy.
Oh, also going out and dancing with your friends is great exercise too!