Download a free template from any website or buy a premium one. All of the Blogger templates already have microdata added to them.
BlogPosting Schema in Rich Snippet Testing Tool
What is microdata?
In simplest term, microdata is way to highlight some data from the whole to the search engines.
For example, you have a webpage about your company. It contains 3 paragraphs, in those there paragraphs you have -
name of the company
name of founder
address
phone...
