Fireworks is a great program—sort of a combination of Illustrator and Photoshop. It's a great place to optimize photographs, although Photoshop is better for retouching. Its real strength is the ability to create navbars and disjoint rollovers. The choices for adding texture and other effects to objects is outstanding, and of the CS web applications, it may be the most intuitive program to use.
The following pages are old—referring to CS3 (I think) but I wanted to get them up for you to use. I'll be updating them as we go along, so if something doesn't work right, check back!
I will also be adding more video tutorials. Stay tuned!