Change to event

        public static void CreateSpreadsheetWorkbook(string filepath,string SheetName0)
        {
                SpreadsheetDocument spreadsheetDocument;
                if (System.IO.File.Exists(filepath) == false)
                {
                    // Create a spreadsheet document by supplying the filepath.
                    // By default, AutoSave = true, Editable = true, and Type = xlsx.
                    spreadsheetDocument = SpreadsheetDocument.
                        Create(filepath, SpreadsheetDocumentType.Workbook);
                }
                else
                {
                    spreadsheetDocument = SpreadsheetDocument.Open(filepath, false);
                }

                // Add a WorkbookPart to the document.
                WorkbookPart workbookpart = spreadsheetDocument.AddWorkbookPart();
                workbookpart.Workbook = new DocumentFormat.OpenXml.Spreadsheet.Workbook();

                // Add a WorksheetPart to the WorkbookPart.
                WorksheetPart worksheetPart = workbookpart.AddNewPart<WorksheetPart>();
                worksheetPart.Worksheet = new DocumentFormat.OpenXml.Spreadsheet.Worksheet(new SheetData());

                // Add Sheets to the Workbook.
                DocumentFormat.OpenXml.Spreadsheet.Sheets sheets = spreadsheetDocument.WorkbookPart.Workbook.
                    AppendChild<DocumentFormat.OpenXml.Spreadsheet.Sheets>(new DocumentFormat.OpenXml.Spreadsheet.Sheets());

                // Append a new worksheet and associate it with the workbook.
                Sheet sheet = new Sheet()
                {
                    Id = spreadsheetDocument.WorkbookPart.
                        GetIdOfPart(worksheetPart),
                    SheetId = 1,
                    Name = SheetName0
                };
                sheets.Append(sheet);

                workbookpart.Workbook.Save();

                // Close the document.
                spreadsheetDocument.Close();
        }