A site map is a list of all the pages in a website. Search engines use your website's site map to find the different pages in your site.
The site map for your site is automatically generated when you publish it — there's nothing you need to do. The site map for your site is contained in a file called Sitemap.xml.
A file called robots.txt is also created when you publish your site. This file contains an entry which tells search engines the address of the site map file.