The multilingual website is necessary if you would like to make your website internationally. To make your website support multiple language, only 3 steps are needed.

1. Create the language file for each language
2. Create a parsing file to include different language file based on cookie/session/user profile
3. Include the parsing file in the homepage and use echo to display the content.

For detail, can refer to

http://www.bitrepository.com/php-how-to-add-multi-language-support-to-a-website.html