namespace WpfApplication1
{
    public partial class App : Application
    {
        private static StoreDB storeDB = new StoreDB();
        public static StoreDB StoreDB
        {
            get { return storeDB; }
        }
    }

    public class Product
    {
        private structBook[] array;
        public structBook[] Array
        {
            get { return Array; }
            set { array = value; }
        }
    }

    public class StoreDB
    {
        public structBook[] GetNumder()
        {
            structBook[] Array  = new structBook[ 6 ];

            Array[ 1 ].iVolume =  10 ;
            Array[ 2 ].iVolume =  1 ;
            Array[ 3 ].iVolume =  502 ;
            Array[ 4 ].iVolume =  1 ;
            Array[ 5 ].iVolume =  10 ;
            Array[ 1 ].dSize =  1586 . 80 ;
            Array[ 2 ].dSize =  1586 . 13 ;
            Array[ 3 ].dSize =  1586 . 00 ;
            Array[ 4 ].dSize =  1585 . 90 ;
            Array[ 5 ].dSize =  1585 . 41 ;

            return Array;
        }
    }
    //формат структуры
    public struct structBook
    {
        public int iVolume;
        public double dSize;
    }
}

namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            //по нажатию кнопки на window закрепляю источник данных, но что делать дальше не знаю
            dataGrid1.ItemsSource = App.StoreDB.GetNumder();

            //dockPanel1.DataContext = App.StoreDB.GetNumder(); ???
        }
    }
}

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="523" Width="591" xmlns:my="http://schemas.microsoft.com/wpf/2008/toolkit">
    <DockPanel Height="474" Name="dockPanel1" Width="549" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="0">
        <Button Height="79" Name="button1" Width="Auto" DockPanel.Dock="Bottom" Click="button1_Click">Button</Button>
        <my:DataGrid AutoGenerateColumns="False" Height="304" Name="dataGrid1" Width="436">
            //???
            <my:DataGrid.Columns>
                <my:DataGridTextColumn Binding="{Binding Path=iVolume}" Header="iVolume" />
                <my:DataGridTextColumn Binding="{Binding Path=dSize}" Header="dSize" />
            </my:DataGrid.Columns>
        </my:DataGrid>
    </DockPanel>
</Window>