Also, I am working from the premise that you have designed the comp for your page in Fireworks, and simply need to harvest the graphics from the comp image. Creating a new frame that will be used as the Over state in our rollovers. Changing objects on the Over frame creates the rollover effect. In most cases, it is best to start from the identical look as your normal view in order to make sure that your over and normal image line up properly. It can be very disturbing to have states of an image off by even one pixel.
Perfection is the minimum standard when creating rollovers.
Creating a new frame is very simple. Activate the Frames window, and make sure that the Frames palette is active. You should have only Frame 1 showing in this window. Click the side arrow on the Frames palette and select Duplicate Frame. Select After Current Frame from the popup that appears and the original frame will be duplicated and appear as Frame 2.