Sitemap Generator is one of the best Sitemap extension for Joomla, download here.
- Install the extension.
- Go to Components -> Sitemap Generator in the backend and use the Generate your sitemap button to start the generation process.
- The sitemap will be saved as sitemap.xml in your Joomla root directory. Be aware that an existing sitemap.xml file would be overwritten without asking.
- Use the "Show the sitemap" button to download your sitemap and check if the generated sitemap is complete.
Note: The Sitemap Generator service allows you to create a sitemap with up to 500 URLs for free.