The CentOS options in your Hostwinds VPS(s) don't come with any graphical user interface by default. There are many options for the look-and-feel of a GUI in Linux, but for lightweight (low resource usage) window management, this guide will use Xfce. These instructions have been tested with CentOS 7 in Hostwinds VPSes.
How To Install a GUI on CentOS
The following commands are to be run as root on your VPS (via SSH or GetVNC)
It is recommended to run a yum upgrade before proceeding to make sure you have the latest version of all packages.
First, install the Xwindows server and system
yum groupinstall "X Window System"
Then Xfce itself
yum groupinstall xfce
Edit ~/.xinitrc to end with 'exec startxfce4.'
echo "exec startxfce4" >> ~/.xinitrc
You can now set up the remote access method of your choice or use Actions -> Get VNC from Cloud Control, login, and run 'startx.'