public static GraphicElement AddElement( 
   GraphicsLayer graphicsLayer,
   MapPoint point,
   string text,
   CIMTextSymbol textSymbol,
   string elementName,
   bool select,
   ElementInfo elementInfo
)

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                    .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
QueuedTask.Run(() =>
{
  //Place symbol in the center of the map
  var extent = MapView.Active.Extent;
  var location = extent.Center;

  //specify a text symbol
  var text_symbol = SymbolFactory.Instance.ConstructTextSymbol
  (ColorFactory.Instance.BlackRGB, 8.5, "Corbel", "Regular");

  graphicsLayer.AddElement(location, text_symbol, "Text Example");
});

//On the QueuedTask
var layout = Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault().GetLayout();
var mapFrame = layout.FindElement("New Map Frame") as MapFrame;

//Get a point in the center of the Map frame
var mapFrameCenterPoint = mapFrame.GetBounds().CenterCoordinate;
//Convert to MapPoint
//At 2.x - var pointInMapFrame = MapPointBuilder.CreateMapPoint(mapFrameCenterPoint);
var pointInMapFrame = MapPointBuilderEx.CreateMapPoint(mapFrameCenterPoint);

//Find the corresponding point in the MapView
var pointOnMap = mapFrame.PageToMap(pointInMapFrame);

//Create a point graphic on the MapView.
var cimGraphicElement = new CIMPointGraphic
{
  Location = pointOnMap,
  Symbol = pointSymbol.MakeSymbolReference()
};
graphicsLayer.AddElement(cimGraphicElement);