There are several places that you must make changes when deploying a multi language website in Magento
1. Firstly change the language in the admin menu System > Configuration, the first tab shown should be General and it includes a Locale section. That is where you set a store's language. You can choose which store it applies to with the scope selection in the top left of the page.
2. Product Attributes - these labels often display on screen dependant on your template and must be updated at catalog > attributes ? manage attributes
3. Next you need to look at the categories and products
4. Now we need to review CMS pages titles, links and content
5. Finally you need to look at your transaction emails in System > Transactional EMails