How to change the Background color of a button dynamically in WPF?

To change the background color of a button dynamically in WPF

System.Windows.Controls.Button b1=new System.Windows.Controls.Button();

b1.Background=System.Windows.Media.Brushes.Blue;

System.Windows.Controls.Button objButtton=new System.Windows.Controls.Button();

objButton.Background=System.Windows.Media.Burshes.Red;