<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
    namespace="Entidades">

  <class name="Carro" table="carro">
    <id name="Id">
      <column name="id" sql-type="Int32" not-null="true"/>
      <generator class="hilo" />
    </id>

    <property name="Descricao">
      <column name="descricao" not-null="true" />
    </property>
    <property name="Fabricante">
      <column name="fabricante" sql-type="Int32"  not-null="true" />
    </property>
  </class>


</hibernate-mapping>

using System;
using System.Collections.Generic;
using System.Text;

namespace Entidades
{
    class Carro
    {
        private Int32 id;
        private string descricao;
        private Int32 fabricante;

        public virtual Int32 Id
        {
            get { return id; }
            set { id = value; }
        }

        public virtual string Descricao
        {
            get { return descricao; }
            set { descricao = value; }
        }

        public virtual Int32 Fabricante
        {
            get { return fabricante; }
            set { fabricante = value; }
        }
    }
}

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <!-- Add this element -->
  <configSections>
    <section
        name="hibernate-configuration"
        type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate"
        />
  </configSections>

  <!-- Add this element -->
  <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
    <session-factory>
      <property name="dialect">NHibernate.Dialect.MySQLDialect</property>
      <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
      <property name="connection.driver_class">NHibernate.Driver.MySqlDataDriver</property>
      <property name="connection.connection_string">Server=localhost;Database=hibexamples;User ID=root;Password=123456</property>

    </session-factory>
  </hibernate-configuration>
</configuration>