If you want to change permissions on a file, the command to use would be chmod. To change ownership of a file/directory, you'd use the chown command.
Try "man chown" and "man chmod" for the manpage entries for both commands. You can also do a search using apropos to search the manpages that contain information on these (or any other) commands ($ apropos chmod)
I found a pretty good tutorial that explains this in greater detail, as well as covers other things such as umnask, sticky bits, etc. here:
http://www.linuxpowered.com/html/editorials/file.html
Hope this helps! (Sorry if I misunderstood the original question)