U.S citizenship answer please?

I would say sorry for my english is not very good anyway i would ask if i could get the u.s citizenship i come form ecuador and my father he is an american Citizen but he would not giving me the u.s citizenship so i would ask how can I get U.S citizenship ? he lives in Miami and now I live in Italy please help me because i want to go to he USA to study i was forgetting to say that i'm 18 and so i'm adult