Your OS9 System isn't set up for networking/file transfer (not the same as connecting to the internet). Chances are AppleTalk is off, or TCP/IP settings are wrong, for example, and file sharing is probably not enabled.
OS9 is a very tight, secure OS (better than virtually any other, including OSX) and you have to turn this stuff on.
For help check out this site (look for file sharing settings with the OS9 computer; ignore the Windows stuff).
Apple's OS9 Help also has probably all the info you need. Check it out, do what it says, and if you still have problems post back (and give us a little more info about what you want to do, exactly, and what hardware/software/network settings you're using).