Install Debian Linux
This Debian image comes with XFCE Desktop. Download Debian 64 bit from the following link and burn in a CD/DVD/Pen Drive. Insert the medium, change the boot option of the computer and start the installation process of Debian 9.https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-9.0.0-amd64-xfce-CD-1.iso
See the below video and familiar with the installation process of Debian 9.
Write down root password and usernames in a diary or a piece of paper.