i would export it as a png? Is that all there is to it?
That would be rather pointless unless you just want to open a raster image in FireWorks.
The usual reason to use Illustrator in conjuction with Fireworks would be to obtain scaleable vector paths which were drawn in Illustrator (a pre-existing logo, for example). Think of it as similar to the ways and reasons you would use Illustrator in conjunction with Flash.
Save the Illustrator file as an Illustrator file (.ai), in whatever is the latest version that your copy of Fireworks can import. Then use Fireworks's Import command. Then you'll have vector paths which you can scale or otherwise manipulate in Fireworks.
Same principle applies to other mainstream vector illustration programs. Most all of them can export their vector paths in .ai format, which you can then import into Fireworks or Flash (or other programs).