am newbie in wordpress.. I've installed its version 3.1.1..

Among the finest to understand how do i result in the publish password protected and just how to include excerpt for this....?

Presuming you mean WordPress 3.1.1, then the reply is that around the page in which you author a publish there's a location to go in an excerpt. Read more within the WordPress codex here: http://codex.wordpress.org/Excerpt

Regarding password protection, you may make a publish password protected or private (various things). Inside a standard Wordpress installation there's a "Publish" panel close to the top right from the page that controls this. This is actually the documentation: http://codex.wordpress.org/Content_Visibility

Modern-day password protection choices are available via plug ins.