How long will it take to get a flat stomach if i just run?

ok so i am 5’11 and i weigh 160 pounds. im 16 years old. im not fat at all but i am a pretty big kid. i am average. i do have a bit of flab though i do want to burn off in the gut section and i wouldnt mind burning off just a little bit of flab in the upper section. what can i do to do this. i dont mind putting on muscle but what i really want to do is just get rid of the little bit of belly fat that i have. i know im young so i will see results quicker then older people so basically what im asking is if i run 2-3 miles a day how long do you think it will take to burn the fat off? is that even what i need to do or if i want an "in shape" look would i have to not burn the fat off but instead fill it out with muscle? please any suggestions.