You basically have two options for file editing from the console, Vi and Pico.
Vi has the most difficult learning curve but is the most powerful editor. Pico is much easier to learn. All the commands are laid out in front of you. Pico, however can have some strange effects on files and is not nearly as powerful as the other two editors.
EnGarde comes with Vi and Pico installed on it. To load the Vi editor simply type:
$ vi fileToEdit
To start the Pico editor type:
$ pico fileToEdit
If you don't enter a filename it will start by editing a blank document.
We recommend using Vi if you will be doing most of your editing from the console. If you don't have experience with vi you'll want to use one of the many resources as it's use may not be immediately obvious.