iterating over an array of custom objects in D

I am having an issue creating some way to iterate or even access elements in an array of custom objects in D.

I have created the array by:

class Database{

public:
    this(){ /* STUBB */}

    void addRow(DataRow input){ this.db ~= input; }

private:
    static uint count;
    DataRow[] db;
}

but when i try and access the individual elements in the array by:

string x = db[1].getCountryName();

I get an error:

Error: no [] operator overload for type Database.Database

It has been a really long time since I've done any coding in C/ C++, and this is my first attempt at D. I'm not exactly sure what to do. how would i go about overloading the [] operator?

By overloading the index operator.

http://dlang.org/operatoroverloading.html#array

For example:

struct A
{
    int opIndex(size_t i1, size_t i2, size_t i3);
}

void test()
{
    A a;
    int i;
    i = a[5,6,7];  // same as i = a.opIndex(5,6,7);
}