ComplexNumber.java I NEED HELPPP

I'm doing programs out of this old java book, I took Computer programming last year at school and used the book but I haven't did the stuff in a while and I'm stuck on a proplem. It says:

Create a class called ComplexNumber that implements complex numbers. The class should have two fields, real and imaginary which hold the real and imaginary parts of the number.

- Create a ComplexNumber object with real and imaginary parts specified by r and i

ComplexNumber (double r, double i)

-Add the complex number represented by c to the ComplexNumber.

void add (ComplexNumber c)

-Multiply the ComplexNumber by the complex number represented by c.

void multiply (ComplexNumber c)

-Return the real portion of the ComplexNumber.

double getReal ()

-Return the imaginary portion of the ComplexNumber.

double getImaginary ()

-Return a String that contains a formatted version of the ComplexNumber.

String formatAsString ()

Create a program called TestComplex that creates two pairs of ComplexNumber objects and outputs them, their sum, and their product.

Any help will be most appreciated.