Hi Palarapu,
Welcome to Visual WebGui
First you should note that the MS SilverLight API has been rapidly changing lately, so rapidly actually that in many cases it requires a new build of Visual WebGui to support it. Within Visual WebGui, Silverlight currently has only Alpha support, which means it is not very stable. In the upcoming version 6.4 release, Silverlight will initially not be supported.
Having said all that, Silverlight can be used within version 6.3.x. You are correct that there are no specific Silverlight application templates in that version, as the Visual WebGui implementation allows you to develop your DHTML and Silverlight application exactly the same until you deploy. Do deploy with a Silverlight presentation you use the Visual WebGui integration tabs (by right clicking your project, select properties and then Deployment). Availability of these Visual WebGui integration tabs depending upon the version of Visual WebGui you have installed.
As per my notes above, there is limited information on how to integrate a SilverLight usercontrol into Visual WebGui, but I think you should explore the Catalog sample application available from the download section and then you might also find relevant information by downloading the source code for the public part of the framework. The Visifire charts distributed with Visual WebGui is an example of a SilverLight component integrated into Visual WebGui. You can find information about using the sources on the wiki here and on getting the Charts up and running on the wiki here.
Hope this helps,
Palli