First steps for a brand new installation:

1. Add check-mk's template and objects files into /etc/nagios/nagios.cfg:

cfg_file=/etc/nagios/conf.d/check_mk_templates.cfg
cfg_file=/etc/nagios/conf.d/check_mk_objects.cfg

2. Edit /etc/check_mk/main.mk and add the hostnames / IPs of the machines you want to monitor.

3. Activate any plugin you may need by symlinking it from /usr/share/check-mk-agent/available-plugins to
   /usr/share/check-mk-agent/plugins.

4. Run check_mk -I and check_mk -O, this will run an inventory check and rebuild your Nagios configuration files.

Additional notes:

The WATO interface is currently not available on Fedora 2X - RHEL 7.X series given the lack of the mod_python package in favor of mod_wsgi. Mod_python is still installable by manual compiling it and that should be the only current way for WATO to work properly on Fedora installations.

The Check-MK upstream is working on porting WATO to mod_wsgi. [1]

[1] http://lists.mathias-kettner.de/pipermail/checkmk-en/2014-February/011450.html