How to upload blogspot Sitemap to Google Webmaster tool

Blogspot (blogger) doesnot allow you to upload any files to it's servers. Basically you cannot add sitemap.xml file to a blogspot blog. However you do not have to create a separate sitemap.xml file it is automatically created for you and it is called atom.xml

So it Google webmaster Tools you can go to upload sitemap and select General Sitemap and type atom.xml in the given text box and submit it.