User Language

Go to Admin -> System -> System Settings.  In the Region section, select the language(s) you would like to make available to users under the field User Language Choices.  Here you can also set the Default System Language.

Each user can have a preferred language designated by going to Admin -> System -> Users. Select a user to edit,  set the user's Language field, and then click Save at the top of the page.

If you would like to modify any of the text that is displayed in the system, go to Tools -> Language Editor. Search for the text or phrase you would like to modify, then enter in your preferred phrasing. Click Save when done. Users may need to log out and back in to see your changes.