[I'm from the old-world of Linux - the new-world is different. I'm retired so getting help is difficult]
I have a HDD with multiple partitions:
/sda6 is the main Linux O/S. /sda2 is an additional image.
I want to make a bootable partition of /sda6.
I booted /sda2, mounted /sda6, Did a "cd" to it, tar'd the image to a thumb drive., then installed the image to /sda3.
What do I need to do to make /sda3 come to life? (in ancient days I'd just edit lilo.conf, add it in, run lilo, and that was it).
<I don't want to say what I've done trying to get it to work because it might mess-up someone's thought path and have him miss a step in what I need to do>.