Using the "newintro" Command

I'm trying to update the introductory message that my list subscribers
receive upon successful subscription to my list.
 
According to the "ReadMe" file at
http://www.greatcircle.com/majordomo/README
I should use the "newintro" command; however, it gives no example of the
syntax.  (I've tried several variations and all with no success.)
 
Could anyone give me the correct syntax for that command, or perhaps direct
me to a more comprehensive list of the commands and their uses?
 
Thanks!
 
-Lisa