interface "ifunction"

Question

1.craete a class called "car" with 2 data members namely :"No Of doors" and "no of wheels" create 2 methods to accept the values of the said data members and to display the values on the screen. create an object to test the above class;

2.create an interface called "ifunction" and put signature of 2 methods namely"getfueltype" and "setfueltype" function will return the fueltype of the car such as petrol,diesal etc and setfueltype fun will set the fueltype of the car . after creationg the interface modify the above car class to implement the interface

=plz help me...
with explanation..
y because i wanna explain