Make a bootable USB with your distro of choice. To do that download the .iso file and use a tool like balena etcher to write that iso to a flash drive (4 GB is usually enough for this). Be aware doing this wipes everything off the flash drive so back up anything important. Reboot the computer and mash esc, f1, f2, f11, f12 (those are the most common ones I’ve noticed). You should either pop up into the bios or into a boot selection process. If you’re in the bios just tell it to go to a boot menu, if you’re in the boot menu pick your flash drive and run through the steps there.

I would start trying it out. Download the image, get an empty usb stick of serious size (32GB or more, up from 8 should be no problem though if you can find it) and use eg Rufus Disk Imagerto install it on the usb stick. When done, restart the computer i to the bios or boot menu (look at the message when starting, f1 f2 del or enter should drop you into bios, f12 on some computers drops you straight into a boot menu).
Feom bios go to boot menu, from boot menu to usb stick and select the option “boot from usb stick”.
Note the login and password should be in the documentation close to the image.