Creating sitemap is very simple and this sitemap works for both 
self-hosted Blogger blogs and normal Blogger blogs. Just use this (
atom.xml?redirect=false&start-index=1&max-results=500)next to your blogs URL. See example below.
http://yourblogname.blogspot.com/
atom.xml?redirect=false&start-index=1&max-results=500
Now you have created sitemap for your Blogger blog, but you need to 
tell search engines about your sitemap so that bots can know your site 
structure. There are two ways to tell search engines about your sitemap.
1. Showing your sitemap in robots.txt file and 2. Submitting your sitemaps in Google webmaster tools
Adding your Blogger sitemap in robots.txt file
Login to your 
Blogger blog and go to 
dashboard >> settings >> search preferences
 and edit the custom robots.txt. Enable and paste the following text and
 click save changes. Make sure to change your blog name in Blogger 
sitemap below.
| 5 | Sitemap: http://sureyea.blogspot.in/atom.xml?redirect=false&start-index=1&max-results=500 | 
 
 
 
So whenever search engines crawls your site they will access your Blogger sitemap from robots.txt file.
Submitting your Blogger sitemap in Google webmaster tools
Login to your 
Google webmaster tools and select you website. In your site dashboard click sitemaps below. Now click add/test sitemaps, add your sitemap (just the
 atom.xml?redirect=false&start-index=1&max-results=500) and submit your sitemap.