This line says server is not declared.
Dim DecodedString As String = server.UrlDecode(context.Request.Form(\"DeckName\"))
I have imports system
Use HttpUtility instead.
HttpUtility
Dim decodedUrl As String = HttpUtility.UrlDecode(encodedUrl)
More details here: http://msdn.microsoft.com/en-us/library/system.web.httputility.urldecode.aspx