Overview

The following documentation is based upon Imre's Create Multilanguge Website

Basically, transforming an existing Joomla website into a Joomla multilanguage website is nothing more than duplicating your content (categories, articles, menus, menu items, modules) and assigning all this to a separate language.

As alternative you can use 3'rd party extensions like Falang or JomFish.

Before start, disable or clear your cache to be sure no interference will appear. Finally, if you use any SEO plugins (JoomSEF, Sh404SEF, SEOSimple, MijoSEF) 
Your's language means e.g. Spanish, French whatever languages you are using. These steps needs to be followed for every new language.

Install your language pack

Since we want Joomla to generate language specific strings on our site (and even on our backend if we want to), we first have to install the (Your's) language pack. (After installation, the new language will appear under Extensions > Language Manager. It shows up both under the tabs Installed – Site and Installed – Administrator.)

Filter a specific language

By enabling functionality to filter a specific language, we can ask Joomla to discover the language that’s been used in the browser of our visitor. In that way, Joomla will automatically provide the visitor with his preferred language. This is the case whenever there’s a match between the browser settings language of the visitor and one of the languages that’s installed in our Joomla website. If there’s no match, the visitor will be shown the default language.

When a visitor of your site is looking at your English listings, by switching to the (Your's) language (see A Language Switch Module) Joomla will know that you still want to see the Extension Listing, but in Your's language. (If you don’t use menu item associations, Joomla will send the user to the homepage what’s not exactly something we want to happen.)

Enable second language for JomHoliday 

Assuming that you already have an English categories (language also set to English), duplicate category (Save as copy) and edit it's details. Go to Publishing tab and sets desired language than Save. Do that for every category. 

Do the same for the Custom fields and Listings. If necessary also Addresses and Reviews.

Duplicate menu

We need to duplicate our current menu, so menus are available for each one of the installed languages. First, we assign the current menu to the English language.


Now create Your's language menu.

Duplicate JomHoliday menu items

Since we created a separate menu for each language, we need to duplicate our menu items as well. By default, the current menu items are set to the language All. First, assign them to the English menu.

 

JomHoliday Items link needs to be duplicated for each language.  More about creating menu links can be found here

 

Now duplicate the menu items and assign them to the Your's language menu.

Duplicate the menu placeholders

Now that the menus and menu items are generated for both languages, we need a menu module to publish them on the site. We first assign the English menu to the current menu module.

 

Now duplicate this menu module and assign it to the French menu.

A language switcher module

We want to provide our visitors a way so they can switch to another language. To accomplish this, we’re going to publish the language switcher module. This module uses a dropdown to switch languages, but you can also use little clickable icon flags.