how use a listbox for select items beetween 3 lists?

hi,
i want select 3 categories using 3 listboxes
like this picture show

http://web-are-us.com/images/list.bmp

how can i do that?


thanks for your help :)

Do you want the post code to be selected automatically when the country and city have been select?

no the user must select that i only want auto populate the list by selecting the first and secund list
thanks :)