To see a list of commands you can press "
/" in a conversation window. After a short while a list will popup with all the available commands (including the commands which scripts added)..
Once that toolwindow is shown you can hoover over a command with your mouse cursor and a short explaination will be given in the tooltip...
Many commands are also available from the Plus! menu in a conversation window: Plus! > Send Command > ...
To be able to use commands you must enable them:
Plus! > Preferences > Conversations > Main > Enable commands
/ 
