Aap table export to excel

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C#

C#4.0

hi i am exporting asp tables to excel but i want to make table headers non-editable please guide me....

Response.ClearContent();
                string filename = "FY15 Input Collection Template_" + ddlcity.SelectedItem.Text + ".xls";
                Response.AddHeader("content-disposition", "attachment;filename=" + filename);
                Response.Charset = "UTF-8";
                Response.ContentType = "application/vnd.ms-excel";
                StringWriter tw = new StringWriter();
                HtmlTextWriter hw = new HtmlTextWriter(tw);
                Microsoft.Office.Interop.Excel.ApplicationClass _ExcelApp = new Microsoft.Office.Interop.Excel.ApplicationClass();
                _ExcelApp.DisplayAlerts = false;
                tbcity.RenderControl(hw);
                tbannualpercent.RenderControl(hw);
                tblasm.RenderControl(hw);
                tbtwotable.RenderControl(hw);
                tbsectb.RenderControl(hw);
                tbthreetb.RenderControl(hw);
                tbthirdtb.RenderControl(hw);
                this.EnableViewState = false;
                Response.Write(tw.ToString());
                Response.Flush();
                Response.End();

this is how i tried its exporting to excel but how can i make table headers as non-editable in excel...i am not getting excel sheet instance to lock cells please any one help me...