How can I lose belly fat with simple excirses?

I’m 15 years old and I’m not to skinny or fat. I’m just in the middle but I’m starting to gain weight and its mostly the front bottom belly fat. I just want any requested on any type of food to eat and any simple excirses with be helpfull too. OH haha by the way and my thighs.
Can you tell me how long it would take also? Thank you (: