Naev includes a galaxy editor that can be used to edit the game world in a graphical environment. The editor can be opened from the game's main menu, but the button for it is hidden by default. To unhide it, you must start the game in "developer mode". To do so, add the --devmode command line parameter to the startup command:
On Mac OS X:
open -a /Applications/naev.app --args -devmode
Alternatively, you can edit your conf.lua file and change
devmode = false
devmode = true
This will cause Naev to always start in developer mode.