There are several documents that will get you started.
It is now recommended that you change selinux setting to permissive and not disabled as it appears in some documentation. Also if you need to leave the firewall enabled you can do that. The developers has provided some guidance on what firewalld rules need to be configured. Or you can just disable the firewalld service as outlined in the docs. Its also best practices to create a new vmdk (virtual disk) for your images and then mount the new vmdk onto the root partition over the /images directory. I have a document on doing that if you need.
At its most basic step its just installing centos 7 selecting bare minimum configuration, then installing wget, git, and then downloading the fog installers.
This one is a bit dated and created by some third party, but the steps are almost the same today: http://blog.ibuddy.info/index.php/2015/06/fog-v-1-3-on-centos-7-full-install-guide/