convert simple site to support multiple languages

I have a simple site written in PHP that will need to be converted to many different languages. I know if the code is organized properly then each element of the site that displays a message is looked up by language to display the message. Your job is to create the paradigm for multi language support so that we can continue building out our site under this new paradigm. A language selection button will be added to the site such that it will automatically refresh in the new language and that will be the language of the site. You don't have to do the translation, but it would be helpful if you new one additional language other than english that we could do the testing with. In your bid, please let me know if you can write the code only or if you can also help in translating into another language. There are less than 10 pages on the site now. There are only a few words and buttons on each page. All together we are talking about 50 words or phrases that need to be translated.