Check the recommended system requirements
Download the ISO.
Burn a DVD or create a bootable USB stick
Boot from the DVD or USB stick to check your computer is compatible with Ubuntu
Back up your important files (in the unlikely event that the installation fails)
Install Ubuntu Budgie
Needs to be prominently displayed on the Downloads page (possibly)
https://www.ubuntu.com/download/desktop/install-ubuntu-desktop
at a high-level