JQuerry Select Box problem



I'm trying to do this using jQuery (in RoR ) and i need some help...

So let me explain it in a few steps. Lets say Selection Box 1 is list
of Continets. I want to be able to fill Selection Box 2 (list of all
countries on selected continent) by selecting a value in Select Box 1.
After that is filled, I want to be
able to handpick few countries and put them in Selection Box 3 in
which I would be able to move them up or down.

Any solutions?

Thanks in advance