Follow the next steps in order to make your website multilingual.
1. Install WordPress Multisite (http://bit.ly/1djeLqW)
NOTE: When you install the network we recommend to use Sub-directories — a path-based network in which on-demand sites use paths. If you don't see this option, edit your functions.php file and add the next code:
add_filter( 'allow_subdirectory_install', create_function( '', 'return true;' ) );
2. Add a new site for example: "en", "fr","es" etc.
3. Go to each website settings and choose "Site Language".
4. In the theme folder we have already 2 languages included (en and fr), I recommend to use the Codestyling Localization plugin to translate the theme. http://wordpress.org/extend/plugins/codestyling-localization/
5. In the version 1.0.7 we added a new menu for languages, select it and add custom links to make connections between sites.
And Voilà! You saved the money for the plugin!