public static GraphicElement AddElement( 
   GraphicsLayer graphicsLayer,
   Geometry geometry,
   CIMSymbol symbol,
   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 symbol
      var pt_symbol = SymbolFactory.Instance.ConstructPointSymbol(
                            ColorFactory.Instance.GreenRGB);

      //create a CIMGraphic 
      var graphic = new CIMPointGraphic()
      {
        Symbol = pt_symbol.MakeSymbolReference(),
        Location = location //center of map
      };
      graphicsLayer.AddElement(graphic);
    });

//On the QueuedTask
//Place a line symbol using the extent's lower left and upper right corner.
var extent = MapView.Active.Extent;
//get the lower left corner of the extent
var pointFromCoordinates = new Coordinate2D(extent.XMin, extent.YMin);
//get the upper right corner of the extent
var pointToCoordinates = new Coordinate2D(extent.XMax, extent.YMax);
List<Coordinate2D> points = new List<Coordinate2D> { pointFromCoordinates, pointToCoordinates };
//create the polyline
var lineSegment = PolylineBuilderEx.CreatePolyline(points);

//specify a symbol
var line_symbol = SymbolFactory.Instance.ConstructLineSymbol(
                      ColorFactory.Instance.GreenRGB);

//create a CIMGraphic 
var graphic = new CIMLineGraphic()
{
  Symbol = line_symbol.MakeSymbolReference(),
  Line = lineSegment,
};
graphicsLayer.AddElement(graphic);

//On the QueuedTask
//Place a polygon symbol using the mapview extent geometry
var extent = MapView.Active.Extent;
//Contract the extent
var polygonEnv = extent.Expand(-100000, -90000, false);
//create a polygon using the envelope
var polygon = PolygonBuilderEx.CreatePolygon(polygonEnv);

//specify a symbol
var poly_symbol = SymbolFactory.Instance.ConstructPolygonSymbol(
                      ColorFactory.Instance.GreenRGB);

//create a CIMGraphic 
var graphic = new CIMPolygonGraphic()
{
  Symbol = poly_symbol.MakeSymbolReference(),
  Polygon = polygon,
};
graphicsLayer.AddElement(graphic);

//On the QueuedTask
//Place a multipoint graphic using the mapview extent geometry
var extent = MapView.Active.Extent;
//Contract the extent
var polygonEnv = extent.Expand(-100000, -90000, false);
//create a polygon using the envelope
var polygon = PolygonBuilderEx.CreatePolygon(polygonEnv);
//Create MultipPoints from the polygon
var multiPoints = MultipointBuilderEx.CreateMultipoint(polygon);
//specify a symbol
var point_symbol = SymbolFactory.Instance.ConstructPointSymbol(
                      ColorFactory.Instance.GreenRGB);

//create a CIMGraphic 
var graphic = new CIMMultipointGraphic
{
  Symbol = point_symbol.MakeSymbolReference(),
  Multipoint = multiPoints
};
graphicsLayer.AddElement(graphic);

    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 symbol
      var pt_symbol = SymbolFactory.Instance.ConstructPointSymbol(
                            ColorFactory.Instance.GreenRGB);        
      graphicsLayer.AddElement(location, pt_symbol);
    });

//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);