The following are links to programs that support --> Google Sitemaps http://www.google.com/webmasters/sitemaps/docs/en/protocol.html or you can go to --> http://code.google.com/sm_thirdparty.html
A sitemap is a file with EVERY SINGLE link on your website whether it is a advertisement link or your own link..
Because you Never Heard about SEO and You are newbie in SEO. but Friend, you should read Sticky threads or some old threads before start to post this types Q's. see this Thread, this is the Sticky and first thread of Sitemap Category, you should check this types threads in all the category so you can get better ideas and You are asking , what is the sitemap ??????? http://forums.digitalpoint.com/showthread.php?t=531765 Any way, but now read and check all the topics of Google sitemap in this URL. after that if you've any query so you can ask here. Thanks John
It is always advisable to make a search on DP before creating a thread. This question has been answered a number of times. Anyways, a sitemap is the map of your site and it is very important as it helps in better indexing, crawing of the website.
To know the Sitemap definition usage and tips, follow the post http://techcupid.blogspot.com/2008/05/sitemaps-definition-usage-and-tips.html
If you are interested in knowing the differences between the sitemap kinds that exist, I suggest you check this sitemaps article that explains html, rss feeds, ror, text, xml sitemaps protocol etc.
Google sitemaps are very important for indexing your site and every effort should be made to place each page in a sitemap for google to crawl. Be sure to follow the protocol and it will benefit you in many ways. And something else you might want to consider is a robots.txt file which list all of your sitemaps for easy crawling, google downloads this file daily.