It is very simple to install Java 8 on our VNC plans. First, you'll need to connect via SSH, your SSH port is 6000 if you're on a plan that can use the webviewer.
If you do not know how then you can follow the tutorial available here: https://virmach.com/connect-vps-first-time-via-ssh
The commands you'd need to run in the terminal to install the software are:
sudo apt-get install software-properties-common -y
sudo apt-get install oracle-java8-installer
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
// Verify it's installed.
java -version
If you get errors regarding "sudo" then please run this command: apt-get install sudo
That should cover it, as always if you have issues please contact our support.