Main command message
The /help command will always show the message specified under
Subcommands
For the subcommand to be recognized it has to have en_us version of itself specified in the config.yml
You can simply go to the end of "en_us" section in fonfig and add a subcommand just by typing:
Translating - adding a language
To translate your new command, firstly, you have to add the locale tag of desired language to the "lang" section of the config. You can find full default locale list here.
After that you have to fill in translations of the error messages and your commands to that language section aswell. Example:
Text formatting
You can use default minecraft text formatting. You can find it here.