//create a simple POCO that will be saved in the database
public class Person
{
    public ObjectId Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

//create a database mapping for the Person class
public class PersonMap: MongoClassMap<Person>
{
    protected override void MapEntity(BsonClassMap<Person> cm)
    {
      //mapping is done using the official mongo csharp driver
      cm.AutoMap();
    }
}

//create concrete implementation of mongo session factory
public class MyMongoSessionFactory:AbstractMongoSessionFactory
{
    public MyMongoSessionFactory(MongoSessionFactoryConfig configuration) : base(configuration){}

    protected override void AfterSessionFactoryInitialized(MongoDatabase mongoDatabase)
    {
        //register your defined mappings
        RegisterClassMap(new PersonMap());
    }
}

//the main class
class Program
  {
    static void Main(string[] args)
    {
      //create mongo config
      MongoSessionFactoryConfig mongoConfig = new MongoSessionFactoryConfig("mongodb://localhost:27016/personsdb?safe=true")
      {
        //define the collections
        Collections = new Dictionary<Type, string>()
        {
          //objects of type Person will be saved in the Persons collections
          {typeof (Person), "Persons"}
        }
      };

      //create an instance of your concrete mongo session factory
      var mongoSessionFactory = new MyMongoSessionFactory(mongoConfig);

      //open a mongo session
      IMongoSession mongoSession = mongoSessionFactory.OpenSession();

      //save a person
      Person person = new Person
      {
        Name = "Scott",
        Age = 29
      };
      mongoSession.Save(person);

      //retrieve objects in the person collection
      var savedPersons = mongoSession.Query<Person>();

      //print
      foreach (var savedPerson in savedPersons)
      {
        Console.WriteLine(savedPerson.Name);
      }
      Console.ReadLine();
  }
}