Program.cs

// <Snippet0>
using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;

static void CreateSpreadsheetWorkbook(string filepath)
{
    // <Snippet1>
    // Create a spreadsheet document by supplying the filepath.
    // By default, AutoSave = true, Editable = true, and Type = xlsx.
    using (SpreadsheetDocument spreadsheetDocument = SpreadsheetDocument.Create(filepath, SpreadsheetDocumentType.Workbook))
    {
        // </Snippet1>

        // <Snippet2>
        // Add a WorkbookPart to the document.
        WorkbookPart workbookPart = spreadsheetDocument.AddWorkbookPart();
        workbookPart.Workbook = new Workbook();
        // </Snippet2>

        // <Snippet3>
        // Add a WorksheetPart to the WorkbookPart.
        WorksheetPart worksheetPart = workbookPart.AddNewPart<WorksheetPart>();
        worksheetPart.Worksheet = new Worksheet(new SheetData());

        // Add Sheets to the Workbook.
        Sheets sheets = workbookPart.Workbook.AppendChild(new Sheets());

        // Append a new worksheet and associate it with the workbook.
        Sheet sheet = new Sheet() { Id = workbookPart.GetIdOfPart(worksheetPart), SheetId = 1, Name = "mySheet" };
        sheets.Append(sheet);
        // </Snippet3>

        workbookPart.Workbook.Save();
    }
}
// </Snippet0>

CreateSpreadsheetWorkbook(args[0]);