Welcome to linuxquestions.
"Don't have a clue how to repair, just looking at a Linux prompt. "
You need to repair lilo. Here is a lilo HOWTO.
It is possible to repair lilo from the rescue CD prompt but it is a lot easier to do so from within your installed Red Hat system. Somewhere in the rescue CD you have the option to boot an installed system. Use that to boot into your Linux system. Then repair /etc/lilo.conf. Then run the lilo command to write lilo to the Master Boot Record (MBR) and you should be OK. If not, then use the rescue CD to boot into Linux and try again.
What you do to /etc/lilo.conf depends very much on what operating systems you want to boot and where they are located. You should be able to figure all that out from the HOWTO.
Be prepared. Create a LifeBoat CD.