Im giving just a try here
DoubleAnimation fade = new DoubleAnimation(0.0, 1.0, new Duration(new TimeSpan(0, 0, 0, 0, 1000)));
Storyboard.SetTargetProperty(fade, new PropertyPath(Border.OpacityProperty));
Storyboard myStoryBoard = new Storyboard();
myStoryBoard.Children.Add(fade);
myStoryBoard.Begin(InsertYourContentObjectHere eg.Grid);