Click on create a new translation at the bottom of the application.
Select the language that you want, for example, French.
Use the translation field to make replacements.
When you are ready, go to File -> Save as then save the file with your WordPress locale code inside cariage/languages folder. Example: if you are working with a French WordPress installation your file name will be fr_FR.po
Go to your server via FTP, and upload the language files into your theme (located at wp-content/themes/cariage/languages).