fluxbox is just a window manager and thats it ...
just use whatever you used before, if it was konqueror use konqueror
if it was nautilus, then issue the command
nautilus --no-desktop (try it without the --no-desktop argument to see why you have to use it
)
or you can download one such as Rox, or gentoo (no not the distro
)
or just sort through
these