You may edit various config files that usually reside in /etc on your system
using these menu entries.

Startup configuration files is your /etc/rc.conf file.  This file controls
which daemons and services are initialized at boot time.

The inetd.conf file determines which services, such as ftp and telnet,
are listened for by your machine.

The usermgmt.conf file determines the default behavior of the useradd/userdel 
group of commands, and sets defaults that will be used later when 
deleting or adding users with these commands.

The daily.conf file is the configuration file for the daily cronjob that runs
once each day.  It will determine what things are checked for, and emailed to 
the root user.

The weekly.conf file is the configuration file for the weekly cronjob that runs 
once each week.  It is similar to the daily.conf file.

The security.conf file is the configuration for the security verification
script that is optionally executed by the daily cronjob.  You may configure
which security verifications are run on a daily basis by editing this file.

The sysctl menu allows you to both change current kernel settings, and
cause them to be automatically set on reboot using the /etc/sysctl.conf
file. 

The sshd_config file is the configuration file for the SSH daemon.  See the
manpage for sshd(8) and sshd_config(5) for more details on the configuration
of this daemon.

The localtime menu allows you to set this machine's local timezone.

The mailer.conf file decides which mailer your system runs by default.
NetBSD ships with both postfix and sendmail, though other mailers added
via the package system may be selectable.