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

namespace byow.Objects
{
    public class Category
    {
        private int _categoryId = int.MinValue;
        private int _number = int.MinValue;
        private IList<CategoryLocale> _arrLocale = new List<CategoryLocale>();

        public virtual int CategoryId
        {
            get { return _categoryId; }
            set { _categoryId = value; }
        }

        public virtual int Number
        {
            get { return _number; }
            set { _number = value; }
        }

        public virtual IList<CategoryLocale> Locales
        {
            get { return _arrLocale; }
            set { _arrLocale = value; }
        }
    }
}

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

namespace byow.Objects
{
    public class CategoryLocale
    {
        private int _categoryLocaleId = int.MinValue;
        private string _name = string.Empty;
        private Category _category = null;
        private LocLanguage _locLanguage = null;

        public virtual int CategoryLocaleId
        {
            get { return _categoryLocaleId; }
            set { _categoryLocaleId = value; }
        }

        public virtual string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        public virtual Category Category
        {
            get { return _category; }
            set { _category = value; }
        }

        public virtual LocLanguage LocLanguage
        {
            get { return _locLanguage; }
            set { _locLanguage = value; }
        }
    }
}

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="byow.Objects" assembly="byow.Objects">
  <class name="Category" table="Categories">

    <id name="CategoryId" type="Int32" column="categoryId">
      <generator class="identity"/>
    </id>

    <property name="Number" column="number" type="System.Int32" />

    <bag name="Locales" table="CategoriesLocale">
      <key column="categoryId" />
      <one-to-many class="CategoryLocale" />
    </bag>

  </class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="byow.Objects" assembly="byow.Objects">
  <class name="CategoryLocale" table="CategoriesLocale">

    <id name="CategoryLocaleId" type="Int32" column="categoryLocaleId">
      <generator class="identity"/>
    </id>

    <property name="Name" column="name" type="String" />   
    <many-to-one name="Category" column="categoryId" />
    <many-to-one name="LocLanguage" column="locLanguageId" />

  </class>
</hibernate-mapping>

// create Locale
CategoryLocale cl = new CategoryLocale();
cl.Name = "brown";

// create and assign language to Locale
cl.LocLanguage = new LocLanguage();
cl.LocLanguage.LocLanguageId = 1;
cl.LocLanguage.CultureName = "en-CA";

// create Category
Category cat = new Category();
cat.Number = 222;

// add Locale to Category
cat.Locales.Add(cl);
cl.Category = cat;

// save Category
this.NHSession.SaveOrUpdate(cat);