Hello! I am trying Linux for the first time. I know nothing about the software.

I downloaded lubuntu onto a USB drive and started it on my dell Laptop (10 years old). I got the errors
/SLUG not found
You need to load the kernel first.

What is a kernel? How do I load the kernel?

I figured out how to get to the command prompts but none of the codes I tried worked. Only "ls" worked and brought up a list of things I don't understand.