generate pdf doc

Hi,
This code generate a pdf report from an ssrsReport. If I want to generate a pdf report from xls file. what changes I need to do in this code?
My 2nd Question,  is this line of code>>  byte[] ret = rpt.Render(System.Configuration.ConfigurationSettings.AppSettings["ssrsReportEmployeeList"], Reporting.Format.PDF, d);
means that I am getting an ssrs report created by Reporting services into a byte format, then in this code >>  Response.BinaryWrite(ret);
I am converting the byte into a binary output so I can view the report output. please explain.... thanks Bob

        protected void btnPrint_Click()
        { // generate pdf file
            string MyId = Request.QueryString["ID"];
           
     ...