Before we start you make also like to look at some of my previous posts: Tiny facebook gadget (add to your blogger) Another social bookmarking using image swapping
Now,Installing it to the blogger below every post is like every other social bookmarking bar ,there is an Html with a css supporting it, on the top of it working the Jquery.
Copy this CSS code and paste it above ]]></b:skin> in your template code ,no need to expand widget template.
First one includes jquery library from google's CDN and the second one is rotating social file.
To show the code below every post paste this HTML code below <data:post.body/>
And save your template Click on view blog to see it working.