Using Silverlight with an Existing Application

This seems like a very simple question, but I haven't found any help on the internet. If you could provide some link or steps for this.

I have created some basic Silverlight applications that work perfectly offline. I also have a basic ASP.NET application with a solution of about 10 class library projects and 1 website. I want to create a small popup that will have some functionality using Silverlight.

How do I need to build this application and how do I integrate it with my existing application so that it appears as a link. I would not like this link to open another application / site.