Getting the Installation Media Ready

Step 1: Download the ISO

Go to the official Ubuntu website and download the latest Long Term Support (LTS) desktop version. LTS releases are supported for many years and are the most stable.

Step 2: Attaching the ISO to the VM

1. In VirtualBox Manager, select the VM you just created (Ubuntu-Linux-Course).
2. Click 'Settings' -> 'Storage'.
3. Under 'Controller: IDE', click the empty CD icon.
4. On the right-hand panel, click the small disc icon next to 'Optical Drive' and select 'Choose/Create a Virtual Optical Disk...'.
5. Navigate to where you saved the downloaded Ubuntu ISO file and select it.

This process tells the virtual computer to 'boot' from the virtual CD (the ISO file) when powered on, just like installing an OS on a physical machine.