use textbox value as excel header

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ASP.NET4

By using gridview send data to excel now i want to send textbox value to excel like date then how to do it?
my code:

string attachment = "attachment; filename=InvoiceReport.xls";
            Response.ClearContent();
            Response.AddHeader("content-disposition", attachment);
          //  Response.AddHeader(Txt_fromdates.Text, attachment);
            Response.ContentType = "application/ms-excel";
           
            StringWriter sw = new StringWriter();
            HtmlTextWriter htw = new HtmlTextWriter(sw);
            grd_forSup.RenderControl(htw);
            
            Response.Write(sw.ToString());
            Response.End();