Sitemap faster is very simple to install in Joomla
1/ Download the zip file "sitemap xml faster joomla joomla 3 and 2.5" below
2/ In your Joomla administration go to extension and install the zip download free
3/ And now you are ready to have your sitemap joomla by going to the Joomla administration component / sitemapfaster
4/ The list appears on your URLs directly, you just have to click on the icon to download sitemap faster (there are 2 link that's normal because new users of joomla don't find the principal button).
Download your sitemap for Joomla
NEW sitemapfaster for joomla last version without the ID here
You can find your sitemap Joomla quicly here