With blogger, it's already there, check the robots.txt file for the URL to the sitemap. Once you have it be sure to submit the sitemap to the major search engines
Just sign up for webmaster tool and add you blog there ... And then add site map... Sitmap's links is available at then end of your blogs page by default... Copy and paste it there....
if you do it from blogger.com amd have same gmail account then it is automaticaly add in you webmaster account... You only need to add the sitemap their....
you can use atom.xml . http://{your blogger url}/atom.xml as your site map. for submitting your site map to Google, you can use like this.
If you use a feed redirect such as Feedburner, you need to use this when you enter you sitemap at Google Webmaster Tools: atom.xml?redirect=false