How do I install a Desktop/GUI on my Linode?

You can install a desktop environment, or any other software that runs in a KVM hypervisor on your Linode. I was able to dig up this guide on using VNC with Ubuntu 16.04 LTS, as well as this guide on Apache Guacamole, which includes a section on VNC.

That said, while you can install a desktop environment on your Linode, in most cases I would caution against it. Linux servers rarely use desktop environments, and you will find that any support you encounter for a Linux server will typically assume you are working from a terminal, and direct you back to the command line anyway. Desktop environments require a lot more resources - some of which are lacking in servers (e.g. graphics cards), and so you may find that performance suffers quite a bit when you have one installed, and it may even require moving up to a more powerful/expensive plan, depending on what plan you are currently using, and what other software you have installed on the Linode.

Controlling desktops over VNC is also quite sluggish in most cases. If the goal of installing a desktop environment is to ease administrative tasks, you may want to consider instead using a web-based control panel software, such as cPanel or VestaCP. You can find guidance on choosing a control panel in our guide.

Okay, you can also get an easy guide at featout.com.

Ubuntu: https://featout.com/linux-server-in-graphical-mode-ubuntu/

CentOS: https://featout.com/linux-server-in-graphical-mode-centos/

Or you can use Glish and this guide:

https://www.linode.com/docs/platform/manager/using-the-linode-graphical-shell-glish/

Thats for debian, but it would work for any of the desktop environments and Ubuntu and gives you browser access (through Glish).

Regards

Mark