Export to excel in c#

string path = Application.StartupPath;
                    Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
                    app.Visible = true;
                    app.DisplayFullScreen = true;
                    Excel.Workbook wb = app.Workbooks.Add(1);
                    Excel.Worksheet ws = (Excel.Worksheet)wb.Worksheets[1];
                    app.ActiveWindow.DisplayGridlines = true;
                    Excel.Range ChartRange;
                    ws.Shapes.AddPicture(path + "\\Tareta_Image.jpg", Microsoft.Office.Core.MsoTriState.msoFalse, Microsoft.Office.Core.MsoTriState.msoCTrue, 0, 0, 170, 28);

                    ws.Cells[4, 3] = "Key Events Report";
                    ws.Cells[4, 4] = "From:" + Date1.Text + "  To:" + Date2.Text + "";
                    ws.Cells[5, 2] = "Asset Number";
                    ws.Cells[5, 3] = "Asset Description";
                    ws.Cells[5, 4] = "Event Description";
                    ws.Cells[5, 5] = "Event Date";
                    ChartRange = ws.get_Range("c4", "d4");
                    ChartRange.Font.Bold = true;
                    ChartRange.Font.Name = "Microsoft Sans Serif";
                    ChartRange.Font.Size = 11;
                    ChartRange.Font.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.FromArgb(90, 90, 90));
                    

                    ChartRange = ws.get_Range("b5", "e5");
                    ChartRange.BorderAround(Excel.XlLineStyle.xlContinuous, Excel.XlBorderWeight.xlThin, Excel.XlColorIndex.xlColorIndexAutomatic,1);
                    ChartRange.Font.Bold = true;
                    ChartRange.Font.Name = "Microsoft Sans Serif";
                    ChartRange.Interior.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.FromArgb(97, 97, 97));
                    ChartRange.Font.Color=System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.FromArgb(255,255,255));
                    ChartRange.Interior.Pattern = Excel.XlPattern.xlPatternSolid;
                    
                    
                    ChartRange.Font.Size = 10;
                    int k = 7;
                    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
                    {
                        ws.Cells[k, 2] = Excel.XlHAlign.xlHAlignCenter;
                        ws.Cells[k, 2] = ds.Tables[0].Rows[i]["fldAssetNo"].ToString();
                        
                        ws.Cells[k, 3] = ds.Tables[0].Rows[i]["fldAssetDescription"].ToString();
                        ws.Cells[k, 4] = ds.Tables[0].Rows[i]["fldEventDescription"].ToString();
                        ws.Cells[k, 5] = Convert.ToDateTime(ds.Tables[0].Rows[i]["fldEventDate"].ToString()).ToShortDateString();
                        k++;
                    }
                    k = k + 1;
                    ws.Cells[k, 3] = "***** End of the Report *****";
                    ws.Columns.AutoFit();
                }
                else
                {
                    MessageBox.Show("No data to Show");
                }


Response.Clear();
                            Response.Buffer = true;
                            Response.ContentType = "application/vnd.ms-excel";
                            Response.Charset = "";
                            Response.Write("<table><tr><th align="center" colspan="6">Software List By System </th></tr></table>");
                            System.IO.StringWriter tw = new System.IO.StringWriter();
                            System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
                            GV.RenderControl(hw);
                            Response.AddHeader("Content-Disposition", "attachment;filename=SoftwareListBySystem .xls");
                            Response.Write(tw.ToString());
                            Response.Flush();
                            Response.End();