How to create random time whe clicking on button? XAML

How can I create some random time, like 10 seconds. So when I click the button I have to wait 10 seconds to see the new button? My question is how to create that random time? And it has to be in Xaml

My code:

public void randomButton()
        {            
            newBtn.Content = "A New Button";
            Random myRandom = new Random();
            int rand1 = myRandom.Next(0, 400);
            int rand2 = myRandom.Next(0, 400);
            panelButton.Children.Add(newBtn);

            Canvas.SetLeft(newBtn, rand1);
            Canvas.SetTop(newBtn, rand2);

            iRandom = row.Next(-350, 350);
            newBtn.Click += newBtn_Click;
            newBtn.Margin = new Thickness(iRandom, iRandom, 0, 0);
        }

        private void newBtn_Click(object sender, RoutedEventArgs e)
        {
            *// here i want the random time to happen!*
            iRandom = row.Next(-350, 350);
            newBtn.Margin = new Thickness(iRandom, iRandom, 0, 0);
        }

Please help me, I really want to know it! Sorry for my bad Englisch!