To add ISO images of CentOS to Proxmox, run

cd /var/lib/vz/template/iso
wget http://yum.tamu.edu/centos/7/isos/x86_64/CentOS-7-x86_64-Minimal-1503-01.iso
wget http://yum.tamu.edu/centos/6.7/isos/x86_64/CentOS-6.7-x86_64-minimal.iso

Now ISO will be available for Install in new VMs created using ProxMox.

List VMS On ProxMox Server

qm list
lxc-ls
lxc-info