When you access the Translations section for the first time, you have already the default language as the first language you can choose to edit. The words that you used within field labels when building your form in the Form Editor are the starting point for all future translations for a particular form, i.e. they are considered default.
Bellow the default language there is a plus sign and if you click on it a lightbox will pop-up where you can select what other languages you want to add to your form. After you’ve selected the default language, two buttons show up: Add Language and Import Languages. The former is used to create the set of translations pertaining to a new language. The latter is useful if you’ve already set up a multi-language form from where you can import translations.
Important: Copy the tags of the messages that appear on the left in case you want to keep the same structure (e.g. %s is used for links).
You can set up certain conditions in Form Rules that will redirect users to a webpage based on the language they have selected on the form.