How to edit the main menu?

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http://unix.stackexchange.com – I am trying to edit the main menu. There is no menu editor anywhere. I have installed alacarte which doesn't seem to work. Also, someone suggested to me "right clicking on the menu and clicking edit", but there is no option. How are you supposed to edit the menu? I'm using Linux-mint 13 with XFCE. Thank you. (HowTos)