How do i make my apple id account to icloud account

Ok so someone stole my iphone 6 at school and ive been trying to locate it but i can't because i don't have an icloud account. So i've been trying to us my computer to make an icloud account but everytime i try to log in with my apple id it says "Apple ID is valid. But is not an icloud account". i really need help to make an icloud account so i can lock my iphone 6 please help!!!! me