Use a text editor to create /etc/exports. Note: This file should conform to the format described in the exports(5) manual page. To view the exports(5) documentation, you can type: man exports in Terminal.
Once /etc/exports has been created, nfsd(8) will automatically start up and start serving the exports.
Using the nfsd(8) command, you can do things like enable/disable the service, cause nfsd(8) to reread /etc/exports, and verify the validity of /etc/exports. To view the nfsd(8) documentation, you can type: man nfsd in Terminal.