if your website in wordpress use this plugin : Google XML Sitemaps for wordpress

Enter your full website URL and some optional parameters in the form below. Press 'Start' button and wait until the site is completely crawled. You will be redirected to the generated sitemap details page, including number of pages, broken links list, XML file content and link to a sitemap file.

You can use the xml-sitemaps creator tool.

You can search google to find the answer