Given that some of the most basic administration involves editing text files, it's your job to learn at least one.
If you're starting at the command line, I recommend pico, which comes as part of the pine mail reader. To start it up, simply type (as either root or as a regular user, depending on what you're trying to edit):
$ pico filenameand follow the helpful menu keys at the bottom of the screen.
If you're looking for a graphical editor, you can try gedit. Beyond that, it's a matter of personal taste, which I'm not going to get into.