Recently Google Webmaster Tools (GWT) simplified the interface for Sitemap submission. As illustrated in this article, Sitemap submission earlier involved the selection of a file type. The new simplified interface, however, eliminates that need, giving us one factor less to worry about.
Login to GWT and go to Sitemaps -> Overview. Enter the path of your Sitemap file, relative to your blog's root, in the given text field and click Submit Sitemap. For Blogger blogs, the default RSS feed can be used as the Sitemap. Given below is relative path of such a feed.
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:
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.
Once submitted GWT will automatically determine the Sitemap type and then start processing it. The figure below illustrates this new interface.