Ubuntu :: Unable To Configure Openbox Settings ?

I have just installed Lubuntu (from Ubuntu). I would like to add a few items to the right-click menu. I tried doing it using ObMenu as well as directly by editing the configuration files in /home/{user}/.config/openbox, but the default remains unchanged (even after reloading the configurations from the right-click menu or rebooting). Could someone give detailed instructions (e.g. where should I add some apps so as to see on the right click applications list?). The default on my right-click are a file manager, a browser and a terminal.

Also, I dont see a way to edit the main menu (the one at the lower left corner of my screen) anymore, although I remember to have accessed it from the main menu somewhere.