Install language packs manually
To manually follow the language pack, you need to upload the language pack in the way described below. Once your installation is successful, the language pack plugin will be enabled by default.
Plugins are usually distributed in the form of jars or the OBRBundle Repository. Want to install a plugin:
Select the configuration icon (cog icon) and select the basic Configuration (general) in the Confluence administrator.
Select the management plug-in (Manage add-ons).
Select the Upload plugin (Upload Plugin).
Select Browse to find the plug-in file you wish to install from your local disk and select it, or enter a URL for the network address.
Select Upload (Upload).
This plugin will be uploaded to confluence and will be installed automatically.
Check the list of user-installed plugins (user-installed plugins) to make sure that the plugin is already available.
If necessary, enable the plugin (some plugins will be automatically enabled after the installation is complete, and some other plugins will need to be started manually from the admin plug-in page after the installation is complete).
Find more Language Packs
Https://www.cwiki.us/display/CONF6ZH/Installing+a+Language+Pack
Confluence 6 Manually install language packs and find more language packs