Creating 2 level menu using single sprite image

programming web dev
1

I have a sprite which is a two level menu. On Rollover of first level menu, the selected item gets highlighted and reveals its second level menu, on rollover of the second level menu, its selected item gets highlighted.

/Sprite image layout/

First level

First level Rollover

Second level

Second level Rollover

Can any one please point to any resource or help on how to [COLOR=black][FONT=Verdana]achieve the state changes[/FONT][/COLOR].

Thanks