Hello, how to install BB code?
Example
Extra fields for image description (leave it blank if not used)
I don't get what you're asking for. Coppermine supports some BBCodes out of the box. If you need more BBCodes, have a look at this plugin: http://forum.coppermine-gallery.net/index.php/topic,57432.0.html
Additionally, you should also have a look at this plugin: http://forum.coppermine-gallery.net/index.php/topic,65779.0.html