zwrite username will bring up a composition window to send a zephyrgram to the user username; a period (.) on a line by itself will send the message.
subscribe classname * * will subscribe you to the zephyr class classname, so that you will receive the messages sent there.
You can also zwrite -c classname -i instance to send a zephyrgram to class classname, instance instance.
You won't have to type this every time you want to send a zephyrgram, though -- you can navigate to the message you want to reply to, in the view window, and then just hit the r key, which will bring up the correct composition window to reply to that message. If you want to reply to just the sender of a message, and not the class and/or instance, use a capital R instead.
To find out more details about a particular message, navigate to it in the view window, and press i (for information) - a window will pop up with many fields, including the ``host'' (which computer it was sent from) and the full timestamp.
If you want to explore more of the commands available in BarnOwl, you can use the help command, which will bring up the on-line help window, which is a quick reference for common keystrokes as well as a place to start looking for more detailed commands.
Geoffrey G Thomas 2009-02-09