Here is how to do it:First sign in to Google Webmasters. Click on your site to view a dashboard page and from the menu on the left side, expand the "Optimization" option and then click Sitemaps.
Click Submit a Sitemap button and it will ask you to enter the sitemap of your blog. The address of your blog will be already there so you just have to add the remaining part which is:
Overall the code would look something like this:
Thats's all. It helps Google index your blog more efficiently and ultimately provide more traffic to your site via its search engine.