I have two dropdownlist in my app country and state and i have to populate them through an xml file.

I have written the following code: 

ds = new DataSet();

                ds.ReadXml(Server.MapPath("~/country_state.xml"));

                LoadCountryDropdownList();

public void LoadCountryDropdownList()

            {

                ddlCountry.DataTextField = "name";

                ddlCountry.DataValueField = "country_Id";

                ddlCountry.DataSource = ds.Tables["country"];

                ddlCountry.DataBind();

                LoadStateDropdownList(ddlCountry.SelectedValue);

            }

private void LoadStateDropdownList(string country_Id)

        {

}

through this code i have achieved data reading from an xml file is done 

and i have also populate the country dropdownlist list

now i have to populate the state dropdownlist list on the basis of country dropdownlist.