How are entities and libraries for the Apache Solr server organized? I'm trying to understand some basics about Apache Solr server, and particularly how its entities and libraries are organized. 

I've tried to read the documentation but it is hard to understand it without good knowledge of the Java language. 

My goal is to integrate Solr with Drupal 7's Search API location module. I have already got working and configured Solr server but it also requires Solr to be extended with Lucene localation library, and this is actually the part that I don't clearly understand. 

There is a version of Solr with an already compiled location library, but it means that the existing one should be deleted. What I was thinking about: is it possible to just copy the apachesolr/solr (with geo library) directory from that version into existing Solr server as new instance?

Any explanations about this?
Iv updated solr to 3.6 version, it has integrated support for spatial search.