How to protect Excel file with password in J#.NET

package Tutorial27;

/* -----------------------------------------------------------------------------
 * Tutorial 27
 *
 * This tutorial shows how to create an Excel file in J# and
 * encrypt the Excel file by setting the password required for opening the file.
 * ----------------------------------------------------------------------------- */

import System.Console;
import EasyXLS.*;

public class Tutorial27
{
    public Tutorial27()
    {
    }

    /** @attribute System.STAThread() */
    public static void main(String[] args)
    {
        Console.WriteLine("Tutorial 27\n----------\n");

        // Create an instance of the class that exports Excel files, having two sheets
        ExcelDocument workbook = new ExcelDocument(2);
            
        // Set the sheet names
        workbook.easy_getSheetAt(0).setSheetName("First tab");
        workbook.easy_getSheetAt(1).setSheetName("Second tab");

        // Set the password for protecting the Excel file when the file is open
        workbook.easy_getOptions().setPasswordToOpen("password");
                
        // Export Excel file
        Console.WriteLine("Writing file C:\\Samples\\Tutorial27 - protect Excel with password and encryption.xlsx.");
        workbook.easy_WriteXLSXFile("C:\\Samples\\Tutorial27 - protect Excel with password and encryption.xlsx");

        // Confirm export of Excel file
        String sError = workbook.easy_getError();
        if (sError.Equals(""))
            Console.Write("\nFile successfully created. Press Enter to Exit...");
        else
            Console.Write("\nError encountered: " + sError + "\nPress Enter to Exit...");

        // Dispose memory
        workbook.Dispose();

        Console.ReadLine();
    }
}