In probably all install examples this File Editor add-on is one of the first they install.
So, this is easy
- click Supervisor
- click Add-on Store
- look for the File editor add-on
- click on it and in the next screen click on install
- toggle show in sidebar and
- click start
So if everything worked out you can now edit files from within the Home Assistant installation.
There are alternatives. If you like to use a Terminal session please read this
Or wait till I finis the install of Visual Code Studio.