public class TextElement : GraphicElement, ArcGIS.Desktop.Mapping.IElement, System.ComponentModel.INotifyPropertyChanged, System.IComparable, System.IDisposable, System.IEquatable<Element>  

{
  //Create a dynamic text element.

  //Set the string with tags and the location
  String title = @"<dyn type = ""page"" property = ""name"" />";
  Coordinate2D llTitle = new Coordinate2D(6, 2.5);
  //Create with default text properties
  //Note: Must be on QueuedTask.Run
  TextElement titleGraphics = ElementFactory.Instance.CreateTextGraphicElement(
                  layout, TextType.PointText, llTitle.ToMapPoint(), null, title) as TextElement;

  //Modify the text properties
  titleGraphics.SetTextProperties(new TextProperties(title, "Arial", 24, "Bold"));
}

{
  //Update text element properties for an existing text element.
  //Note: Must be on QueuedTask.Run
  // Reference and load the layout associated with the layout item
  if (layout != null)
  {
    // Reference a text element by name
    TextElement txtElm = layout.FindElement("MyTextElement") as TextElement;
    if (txtElm != null)
    {
      double x = 2.0;
      double y = 3.0;
      // Change placement properties
      txtElm.SetAnchor(Anchor.CenterPoint);
      txtElm.SetX(x);
      txtElm.SetY(y);

      // Change TextProperties
      TextProperties txtProperties = new TextProperties(
                        "Hello world", "Times New Roman", 48, "Regular");
      txtElm.SetTextProperties(txtProperties);
    }
  }