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 your MyBB installation’s htdocs/ directory (or you could simply decompress everything and then remove the install/ folder), which by default would be /opt/bitnami/apps/mybb/htdocs/.
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: