Gedit is a plain text editor. If you did not find it with 'which gedit' then I would suspect it is not installed. There are lots of editors for linux. Gedit is a nice one I install on my systems, even though I run KDE mostly. You can install it with your package manager.
If there is something you need to edit before you get gedit installed, almost all distros install 'vi' and or 'vim' by default. They take a little getting used to, but for simple changes, they will run without the X server, or with it.
Hope this helps.