There is a great community site for NHibernate on the Web called the NHibernate Forge. It is located at http://www.nhforge.org/, and it provides a wealth of resources for the new and veteran NHibernate user.
A basic NHibernate project is composed of three major parts. You will need a mapping file to tell NHibernate how the database is or should be (see the Mapping our types section in Chapter 4) constructed, some data access methods to tell NHibernate what data you want to retrieve or store into the database, and a POCO to allow you to interact with the data. While XML mapping files are commonly used in NHibernate projects, they are not the only way to map data to POCOs (more in Chapter 4).
Take a look at some sample files, but don't get too hung up on them. We'll go into more detail in the later chapters.