how can i do this step? or where do i add, i have been getting a few websites flooded by hundreds of ips
If you server is flooded by hundreds of requests from different IPs but with same URL, you can create a General Context to block access to that URL. The Context URI should match or include that URL and Accessible is set to No.
For example, if the server is pounded with "/foo/bar.html", then you can add context with exact URI=/foo/bar.html, or set URI=/foo/ to block all URLs that start with "/foo/".