How can I set up a directory for ftp anonymous?

[Melissa Hines]

Q: How do I set up a directory so that it can be accessed via an ftp anonymous
   session? 

System: DECstation 3100
        Ultrix 3.0 (Rev. 7)

I am a very infrequent UNIX user, so please pardon my ignorance.  Basically,
I would like to set up a directory that other users of a certain Mac software
package could access.  I have asked the "superuser" on this machine for help,
but he couldn't figure out how to do this.

Thanks for any help you can offer!

Melissa A. Hines                Hines at Portia.Stanford.Edu
Dept. of Chemistry
Stanford University