Just adding to Eddy Vluggens answer, to check when a user clicks a certain item you can use the SelectedIndexChanged or SelectedValueChanged Event of the ListBox. You could then check the SelectedItem, SelectedIndex or SelectValue.
As Eddy already pointed out you can then set the SelectedItem, SelectedIndex or SelectValue of your second ListBox.
An example on MSDN[
^]. Good luck!