In order to install Webmin on your CentOS 6.X and CentOS 7.X dedicated server or Cloud VPS, run the following commands via SSH:
wget http://prdownloads.sourceforge.net/webadmin/webmin-1.760-1.noarch.rpm
rpm -U webmin-1.760-1.noarch.rpm
After this Webmin should become available on your Cloud VPS or Dedicated Server IP address, on port 10000.
For example: http://replace_with_your_server_ip_address:10000
then open URL in any modern browsers such as Chrome, Firefox, Safari etc.