Sorry I misunderstood, (maybe I still do!),
If the gradient is the page background, then to be able to see 'through' the footer so you can see the page background, then you would need makes sure that both the outerWrapper and the footer divs have no background colour or images. If you select these divs and check the css panel, you can delete the background colour styles.
You can apply whatever colour or background images you like to the content div (and header div) - the footer will still be see-through (to the page background).
Is this not what you mean? I don't understand where Fireworks comes into it!
This has a transparent footer and outerWrapper divs.