There is only one program you can use in your console to invoke certain actions in fluxbox.
Man-Page:
:~/$ man fluxbox-remote
Display available fluxbox commands. Many of these commands are ment to deal with focussed windows, and can only be used from the window-menu, but the list also has some items useful for fluxbox-remote.
$ fluxbox --list-commands
activate
activatetab
addworkspace
...
workspace
workspacemenu
$ fluxbox-remote exit
# or
$ fluxbox-remote quit
$ fluxbox-remote showdesktop
use this after editing the keys file
$ fluxbox-remote reconfigure
$ fluxbox-remote reloadstyle
This might help when fluxbox starts to behave weird.
$ fluxbox-remote restart