KVM is a kernel space virtualization environment for Linux. It uses virtualization at the processor level and is very efficient. That being said, it requires a high level of command line configuration.
You MUST have processor support in order to use KVM. To determine if your processor can handle kvm run the following:
egrep '(vmx|svm)' --color=always /proc/cpuinfo
Even if your processor is NOT capable of running virtualization, there are some utilities such as disk image conversion which can still be useful. If your processor does not support KVM you can use an alternative such as VirtualBox.
yum install --enablerepo=clearos-core kvm virt-manager libvirt dejavu-lgc-sans-fonts
If you want to use the ClearOS Graphical Desktop to manage your VMs, install the graphical environment here.