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");
});