Create a geometry from a fixed lati/lon and show it on the map

[AndreaIncognito]

I want to draw a point on the map at the fixed latitude/longitude position in the world.
I am using mappoint, but it draw with X Y values.
Please, there is a method ?
Thanks in advance.

[JenniferNery]

MapPoint p = new MapPoint(Longitude, Latitude);
// Project point to Map's spatial reference, use ESRI.ArcGIS.Client.Projection.WebMercator or Geometry Service
graphic.Geometry = p;

You can look at this SDK Sample: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Project