export to csv file

Question

i have two projects one first one is correct(media flow)and 2nd one is not correct(HDI_Silverlight2_DataGridColumns_cs).

in mediaflow project a property like <this:excelcolumn> excelcolumn is class ?

How it is use in my project?

Designing code

<Grid>

          <StackPanel Orientation="Horizontal" Margin="6">

            <data:DataGrid x:Name="results" Margin="6" FontSize="16" >

              <data:DataGrid.ItemsSource>

                <this:Customers/>

              </data:DataGrid.ItemsSource>

            </data:DataGrid>

            <Button Content="export..." VerticalAlignment="Top" Margin="4" FontSize="16"  Click="Button_Click"/>

          </StackPanel>

        </Grid>

public class Customers : List<Customer>

  {

    public Customers()

    {

      this.Add(new Customer("John", "Doe", "Developer"));

      this.Add(new Customer("Jane", "Smith", "Designer"));

      this.Add(new Customer("Bill", "Williams", "Developer"));

      this.Add(new Customer("Robert", "Green", "BDM"));

      this.Add(new Customer("Rita", "White", "Designer"));

      this.Add(new Customer("Karen", "", "Developer, Designer"));

      this.Add(new Customer("Mike", "Cruz", "IT Pro"));

      this.Add(new Customer("", "", "", ""));

    }

  }

  

  public class Customer

  {

    

    public Customer()

    {

    }

    

    public Customer(string first, string last, string role)

    {

      First = first;

      Last = last;

      Role = role;

    }

    public Customer(string first, string last, string role, string notes) : this(first, last, role)

    {

      Notes = notes;

    }

    public string First { get; set; }

    public string Last { get; set; }

    public string Role { get; set; }

    public string Notes { get; set; }

  }