It is pretty easy to have SilverLight app. running in your SharePoint Site.
Here is a example you can add the SilverLight application into the feature then deployed to the server. But for quick test, you can manually.
Just create a new page add insert SilverLight Web Part in, then Go to SilverLight application Bin folder and find .XAP file upload to the same library.
Your config for the web part will look like
If you have configured the web part right and the SilverLight still not showing. Close the IE then open again as there may be cache in your browser.