how to download pdf

 Hi all
I have written code to download pdf file form my web page to client side... my code is
     {

                string lstrFileName = Server.MapPath(@"~\pdfForVVKIUserManual\VVKIUserManualTeachers.pdf");
                string ext = MapPath(@"~\pdfForVVKIUserManual\VVKIUserManualTeachers.pdf");
                string type = "";
                if (ext != null)
                {
                    switch (ext.ToLow ...