Update (Jan 2009):
This article explains the earlier interface of Sitemap submission. For the new simplified interface go here.
In a previous article we looked at how you can submit your site to Google Webmaster Tools (GWT). Once you submit your blog and verify your ownership to GWT, the next step is to add a sitemap.
Put in a simple way, a Sitemap is an XML file carrying the details of the posts in your blog. Because it is an XML file, computers (computer programs to be precise) find it easy to read it. Such files are also known as machine readable files. (Note, however, that the Sitemaps we refer to here are different from the human readable HTML pages that certain web sites carry, which guide the human visitors to all the pages on those sites). These Sitemaps are processed by search engine spiders such as the Googlebot, to discover the pages in web sites/blogs. Sitemaps are particularly useful to be used with blogs that have dynamic content. See the About Sitemaps help topic on GWT help center for more information on them.
The purpose of this article is to illustrate how to add a Sitemap of your blog to GWT. You can accomplish this by following the steps given below.
1) Login to GWT and click Sitemap -> Add for the relevant blog. (if you have submitted more than one blog, all of them will appear in your dashboard)
2) Choose General Site Map from the next screen.
3) Under the 3rd option which reads as My Sitemap URL is, type the following line.
feeds/posts/default?max-items=500&start-index=1
http://[your blog name].blogspot.com/feeds/posts/default is the default RSS feed for your blog. Since the RSS feed is an XML file, that can work as a Sitemap. The two parameters we provided in the above line instruct GWT to take 500 posts starting from the first post, as the content of this Sitemap. Later, if you want to add the second 500 posts, all you have to do is to add another Sitemap which looks like:
feeds/posts/default?max-results=500&start-index=501.
It is not a must to submit 500 posts at a time. It can be any number as long as the Sitemap does not exceed the limit of 50,000 URLs or 10MB in size.
4) Click Add General Site Map
You will see a confirmation page once the Sitemap is successfully added. Be a little patient until the Googlebot consumes this and build up the index for your blog. Remember, it can take well over a month for indexing to happen.
The following figure illustrates the 4 steps just described.