Welcome to LQ.
The command line in Linux scares me to death. I remember the old DOS days, where one mistake makes you have retype the whole effing thing.
As long as you stay away from rm -rf
you'll be okay.
I am also an old DOSsie.
You will find that the the Linux command line is ultimately more logical, and the Linux security model reduces the possibility that you will do irreparable harm to your system. User does not have the authority to modify system settings and files; only root can do that.
Here're some references I think you will find useful.
. It's oriented to Ubuntu, but it's full of good info.
. Machtelt Garrels's Intro to Linux.
. Slackware oriented, but excellent on the basics, such as file structure, permissions, and the like.