How to order array elements randomly in C#?

I'm trying to program a simple game in C# and WPF. The buttons are working fine, the game is almost ready. However, I have to ensure, that the button are sorted randomly at the program start. And I do not really know how to achieve it.

The command Shuffle is obviously false :((

Thank you for any kind of help. Regards, Paul.

namespace WpfApplication1
{
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void button_Click(object sender, RoutedEventArgs e)

    {
        int gedrückterKnopf = 0;
        Button[] knöpfe = {button01, button02, button03, button04, button05, button06, button07, button08, button09, button10, button11, button12, button13, button14, button15, button16 };
        Shuffle(knöpfe);

        for (int i = 0; i < 16; i++)
        {
            if (knöpfe[i] == sender)
            {
                gedrückterKnopf = i;
                break;
            }
        }

        int leerstelle = 0;
        for (int i = 0; i<16; i++)
        {
            if (!knöpfe[i].IsEnabled)
            {
                leerstelle = i;
            }

        }
        //MessageBox.Show(gedrückterKnopf.ToString() + " " + leerstelle.ToString());

        int zeile1 = Grid.GetRow(knöpfe[gedrückterKnopf]);
        int spalte1 = Grid.GetColumn(knöpfe[gedrückterKnopf]);
        int zeile2 = Grid.GetRow(knöpfe[leerstelle]);
        int spalte2 = Grid.GetColumn(knöpfe[leerstelle]);

        if ( (zeile1 == zeile2 - 1 || zeile1 == zeile2 + 1) && spalte1 == spalte2
            ||
            (spalte1 == spalte2 - 1 || spalte1 == spalte2 + 1) && zeile1 == zeile2
            )
        {
            Grid.SetRow(knöpfe[gedrückterKnopf], zeile2);
            Grid.SetColumn(knöpfe[gedrückterKnopf], spalte2);
            Grid.SetRow(knöpfe[leerstelle], zeile1);
            Grid.SetColumn(knöpfe[leerstelle], spalte1);
        }
    }
}

}