How to install mod_cloudflare on centos7 and then configure it in PHP7

Due to the use of cloudflare, my piwik can not display real IP normally. I am distressed because I am not a professional technician.
How to install mod_cloudflare on centos7 and then configure it in PHP7?
Because it is the first contact centos7, it is not familiar with it.
I google a lot of tutorials, it looks like mod_cloudflare installed successfully, but I’m not sure.
I do not know how to configure PHP7, I hope we can get a specific tutorial.
Thank