In order to enable mod_evasive, you nee to add the following line
to your /etc/httpd/httpd.conf file:
  # --- 8< ---
  Include /etc/httpd/extra/mod_evasive.conf
  # --- 8< ---

Once enabled and after restarting Apache httpd, you can test mod_evasive
by running the following command:
  sh /usr/doc/mod_evasive-$VERSION/test/00_regular_config/test.sh

For this test to work, two https virtualhosts called 'a.site' and 'b.site'
need to be setup first, each with their own mod_evasive configuration. You can
also edit /usr/doc/mod_evasive-$VERSION/test/00_regular_config/test.pl and
enter URLs that work for you.

The mod_evasive module for Apache httpd is extensively configurable globally
in the Apache configuration file /etc/httpd/extra/mod_evasive.conf
but you can override these global settings per VirtualHost.
If you want to enable mod_evasive only for specific VirtualHosts then set
  DOSEnabled false
in the global configurationfile /etc/httpd/extra/mod_evasive.conf and then add 
  DOSEnabled true
for individual VirtualHosts.

Configuration is documented in the README.md file which you can find in
the package's documentation directory.