I solved it my self only yar......
please follow the above code to add a utton dynamically and please use the below code to add image to that
FrameworkElementFactory
ControlTemplate ctTempExpand = new ControlTemplate(typeof(Button));
var image = new FrameworkElementFactory(typeof(Image));
ctTempExpand.VisualTree = image;
image.SetValue(Image.SourceProperty, new BitmapImage(new Uri(@"Plus.png", UriKind.RelativeOrAbsolute)));
image.SetValue(Image.HeightProperty, 21.0);
image.SetValue(Image.WidthProperty, 18.0);
fefDelButton .SetValue(Button.TemplateProperty,ctTempExpand);
fefDelButton .SetValue(Button.ToolTipProperty, "Expand");