I followed the Dreamweaver Tutorial, and everything worked perfectly.... Except centering the Golden Gate Bridge image by deleting the W: & H:. It stayed on the left, in the design view as well as testing it on Global Foxfire/Mozilla.
I found on Dreamweaver: Help "Inserting an image" has changed, however I cannot find how to center the image.
The image of the Golden Gate Bridge must be nested inside the hero div. As long as you haven't made some other mistake, removing the width and height of the image will result in it expanding and contracting with the width of the page. See the following screenshot for how the Property inspector should look when you have the image selected in Design view. The Tag selector (highlighted) shows the image nested inside the hero div, which in turn is nested inside the wrapper div.