tes1.php

<?php 
    //call the autoload
    require 'vendor/autoload.php';

    //load phpspreadsheet class using namespaces
    use PhpOffice\PhpSpreadsheet\Spreadsheet;

    //call xlsx writer class to make an xlsx file
    use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

    //make a new spreadsheet object
    $spreadsheet = new Spreadsheet();

    //get current active sheet (first sheet)
    $activeWorksheet = $spreadsheet->getActiveSheet();

    //set the value of cell a1 to "Hello world"
    $activeWorksheet->setCellValue('A1', 'Hello World !');

    //make an xlsx writer object using above spreadsheet
    $writer = new Xlsx($spreadsheet);

    //write the file in current directory
    $writer->save('hello world.xlsx');

    //redirect to the file
    echo "<meta http-equiv='refresh' content='0;url=hello world.xlsx'/>"
?>