Dreamweaver is a lot different of an environment than C5. In fact, they're different kinds of applications -- one a graphic design package for websites and the other a content management system.

I'd suggest installing C5 with the sample website. Just play with it. Figure out how much you can accomplish through the front end -- there's a lot. Find the use and limitations of the various blocks.

It's best not to try to build anything you want to keep at first. Give yourself the freedom to screw things up and reinstall.

As for your Photoshop file, if one of the existing themes is close, that might be the way to go. If, on the other hand, you have familiarity with CSS and some of PHP (or want to), you can roll your own. The free download of the 960 grid is a good place to start.

I think you might find this set of tutorials useful:http://net.tutsplus.com/sessions/photoshop-to-html/.... It doesn't cover C5 though. It's about how to make a website out of a Photoshop file.