Manning has made two chapters from the book available for free download (there isn't much available for free these days) from their MEAP program.
Chapter 2 entitled "Getting started with Hibernate Search" will give you an over-view of Hibernate Search: how to use it, how to express full-text queries, and how it fits into the Hibernate programmatic model.
Chapter 11 entitled "Accessing Lucene natively" starts with looking at Hibernate Search’s SearchFactory, which is the key entry point to Lucene. It also examines the effects that sharding presents, writing a custom DirectoryProvider and what you must take into account when you do.
We’ll also show you how to access the legacy Lucene document and several related values by utilizing a projection, and we’ll demonstrate how it affects performance.
Manning has also provided the book's source code for download from the same link.
Download them, sit back, do a little reading and see what you think.