in OS 9 you can use the personal web hosting... but I would strongly recomend either running linux or os X on the computer. your computer should run all of the PPC linux distros, If you are starting out I would recomend either yellow dog or gentoo. For more info look at
http://penguinppc.org/
yellow dog is a ppc distrobution, so they have a strong focus on the mac
gentoo has one of the best package management systems, and a nice installation guide, so that once you have installed it you can type 'emerge apache' to get a web server.
it just depends what you want...
OS X does have a version of Apache built in, which will work for a basic web server. If you want PHP / Perl / other plugins there are binary distrobutions of apache 2 for os X.
--will