Like gnome Control + alt + L

In Lxde how can i do that? What I have to intall to do this?

thanks

--searching for a solution on my own but...

ok if I do alt+f2 and type xscreensaver-command -lock that's a small solution. tryed to do an small script but it's not working..

this is what I do

vi lock.sh

#!/bin/bash
xscreensaver-command -lock
exit 0

chmod +x lock.sh

but this doesnt work.. ideas?