Modify the interface language
By default, MyBB uses English as its default language, but you can download and install other languages, such as Spanish or Chinese, for example. To download a language pack, browse MyBB’s official site for language packs at http://community.mybb.com/mods.php?action=browse&category=19
To install a language pack, follow these steps:
Download and decompress the images/ and inc/ folders at the /opt/bitnami/mybb/ MyBB installation directory (or you could simply decompress everything and then remove the whole installation’s directory).
To change your MyBB Board’s default language, enter the Administration Control Panel and navigate to “Configuration -> General Configuration”, then change the default language to the one you just installed:
To change your MyBB AdminCP’s language, navigate to “Configuration -> Control Panel Preferences (Global)” and change the language to the one you just installed: