how to install Encore Premiere Pro CSS

What do you mean by CSS... do you mean CS6 ???

CS5-thru-CC PPro/Encore tutorial list http://forums.adobe.com/thread/1448923 will help

The bottom section of the link above has several Adobe links, and other information, on downloading Premiere Pro CS6 and the bundled Encore CS6, and the TWO ADDED downloads for the Encore library content, to author a DVD or BluRay... and the tutorial list includes learning how to use Encore... pay particular attention to the picture in reply 3 at this link - https://forums.adobe.com/thread/1516173 (picture first posted by Ann Bens and reposted by Stan Jones)