How to Begin a French Version of My Site?
Drupal support multi-language websites and creating a multi-language site is very easy.

You can configure a Drupal website to use a language other than English and you can configure a site to use multiple languages.

If your site requires the interface to be displayed in multiple languages or if you need to customize the interface of a single language site, the first step is to enable the multilingual capabilities of Drupal.

You can also configure a Drupal site to allow your users to switch languages and you can translate content into multiple languages.

Helpful Resources:


Multilingual Guide Tutorial
Building a Multi-Language Site
How To: Basic Internationalization Setup 
Translating Site Interfaces      
Translating Content Contributed Modules for Localization and
Internationalization
Core Modules for Localization and
Internationalization
Cookbook: Build a Non-English D7 Website      
Localization API
Internationalization (i18n) module
Book: Drupal 7 Multilingual Sites (Kristen Pol)


Videos:


Building a Multilingual, Multidomain Drupal Site
Multilingual Site Setup and Management
Multilingual Module Madness! Which i18n Modules Do You Really Need?


Getting Started:


Localized Drupal Distribution: A small distribution to install Drupal with user interface translations pulled automatically from localize.drupal.org. It is suggested you use this distribution to start off with Drupal if you'd like to set up a localized site.
Internationalization: This is a collection of modules to extend Drupal core multilingual capabilities and be able to build real life multilingual sites.
Internationalization (i18n) Submodules: A collection of submodules that provides extended multilingual support for Drupal. Each module addresses a specific functionality.
Apache Solr Multilingual: The goal of this project is to cleanly extend Apache Solr Search Integration to provide: better support for non-English languages, support for multilingual search, cross-language information retrieval (CLIR), and an easy-to-use administration interface. Apache Solr Multilingual does not replace Apache Solr Search but is based on it.
Related Modules: A list of additional contributed Drupal 7 modules that extend Drupal's multilingual features