How can i lose some weight and is it anorexia?

im 14 years old im 174cm tall and i weigh 56kg!!!!!!
i am always thinking im fat.. i go back to school in a week and need to lose some weight before then i want to look different so everyone is suprised.
how can i lose some weight!?

eat wheat bread and low fat milk and cut fatty food.

You can discuss your diet with a doctor or registered dietitian to make sure your getting enough calories for growth and bone mass or talk to a mental health professional who specializes in eating disorders, that the best advise I can give you.