Basic Usage

In order to get the list of available commands, simply type : !help

The bot, either directly or in a chatroom will answer you with the list of commands and their meaning.

me:

!help

bot:

Available commands:
ElizaBot: 
!askus: Give us a fun topic to talk about
!complete: Complete the given sentence
!eliza: El'cheapo shrink for you
ErrBot: Commands related to the bot administration 
!install: install a plugin repository from the given source or a known public repo (see !repos to find those).
!load: load a plugin
!reload: reload a plugin
!repos: list the current active plugin repositories
!restart: restart the bot
!status: If I am alive I should be able to respond to this one
!taillog: Display a tail of the log
[...]

You can request more help by doing !help command.

me:

!help weather

bot:

Shows weather info for given location.
Example: !weather San Francisco, CA
or !weather brussels

For the current list of available commands you can look at http://github.com/gbin/err/wiki/Catalog