How to backup a .raw file?

Thank you, the problem is, the backup doesn't seem to backup the entire VM, just the server with the configurations.
To restore, I have to create a new VM, install CentOS 7, install Virtualmin and only then will the restore of the websites work?

I would really like the restore to place all 3 parts. Is this possible?
 
Do you mean that your VM has 2 virtual disks, and you set the Proxmox backup to backup only the first one?
If so, to play safe, I would suggest to shutdown the VM, restore the VM using a different VMID (with qmrestore or with GUI, i.e. your VM 102 restored as 104, if 104 is available). Then you can move (or copy) and rename the 102 second virtual disk to the new position and name.
i.e. cp /var/lib/vz/images/102/vm-102-disk-2.raw /var/lib/vz/images/104/vm-104-disk-2.raw
run the 104 vm, if everything is ok you can destroy 102 and set scheduled backup to backup 104 instead of 102.