How To Add Multiple Language In Magento

• Step 1: Create two stores
  In admin section, go to System menu ->Manage Store then create two stores.
  

• Step 2: Select language for each store
  In admin section, go to System menu -> Configuration. Please select each store in the top left corner, then you can select a language for that store in locale dropdown.
  

• Step 3: Create locale package for each language
  Create two folders: en_US and fr_FR in app/locale folder
  

Now you can go to the front-end and see how it works.