Regarding "HAS A" Relationship

Question

Hi,

I have one doubt regarding understanding of "HAS-A" relationship between classes.
Consider i have two classes : Employee and Address. Now, i want to know when "HAS-A" relation will be implemented?

1) When i am simply creating member in Employee class like :
        private Address empAddress ;
        public Address _Address
        {
             get{}
             set{}
        }

2) when i am creating whole Address class inside Employee class as Nested class.

Thanks,
Himanshu