Adding layers to the map
The ArcGIS Viewer for Silverlight provides the ability to add layers to the map by searching and browsing. Use Search to discover layers from ArcGIS.com or the Web. Use Browse to view the data that is provided by an ArcGIS Server instance that you already know about.
With the Search functionality, you can do the following:
The Browse option allows you to add layers from ArcGIS Server instances. See Browsing ArcGIS Server for more information.