What is PHP solr and how can it communicate with existing PHP website?

Solr is a PHP extention which helps you to communicate with Appache Server. It only works with PHP5 and heigher versions.

You may have a look:

http://www.php.net/manual/en/book.solr.php

You have a look for examples:

http://www.php.net/manual/en/solr.examples.php

thank u sir they r helpful