You’re using a POSIX style platform here. If you’re not familiar with Linux, MacOS X or other UNIX-like things, start here at the Linux for Newbies site. Don’t be ashamed; I have to go there frequently and I admin moderately sized Windows Server networks for a living.
‘vi’ is integrated into Zeroshell for editing text files. From the ZS console, hit ‘s’ to get a bash shell prompt, and then you can use Bash shell commands to browse and edit files:
Now ‘vi’ is an evil editor if you haven’t used it before, so I suggest reviewing it on the Linux for Newbies site. I don’t know if simpler editors exist on the ZS distribution.