In order to add new languages to Freelance Cockpit you just need to copy the english folder in /application/language/ and rename it to the language you want to create.
For example if you like to add german language then you call the new folder german. Now you need to upload a flag for your new language to /assets/blueline/img/yourLanguage.png (the name of the flag icon file must be the same as the language folder name).
Now you are all set to translate the application language lines. Just go to your language folder and change the language lines of all files within the folder.
