This article explain how to use Google sitemaps.

Thanks for the link. Sitemaps can help your site to be crawled easier.

A Google sitemap is for a whole website. Do you own the website, or is your blog just hosted on some blogging site? If it is just hosted then you cannot do a sitemap.
If you own the whole site, then make sure you set it so that the sitemap is readable like a web page. You can check this by trying
http://yoursite/sitemap.xml
That assumes your sitemap file is named sitemap.xml
Then go to Google, sign in and go to webmaster tools. You will be able to submit the url.
Source(s):
http://www.sitemaps.org/protocol.php#loc...

Also, using sitemaps visitors will have an easier time to navigate your site and it may encourage more traffic.