how to add plus one button in blog
Google Plus one button is really important in order to improve your search engine ranking because if you add this and if some one +1 it then its is counted as refer. This is used to make a spam free search and this strategy of google is really nice.
You can add the button after you go to the link
http://www.google.com/webmasters/+1/button/
You can customize, make size and then add it to your blog.