under-deck "carport" needs a proper roof...

I live in the Santa Cruz mountains, about 12 miles from the ocean. We get a lot of rain and fog in the winter. We've only been in this house for about 1.5 years. It's a fixer, and I've done several things, some fairly major. Anyways, there is a deck on the front of the house, and to keep the rain out, the previous owner put plywood under the redwood decking. The plywood is now moldy, and I'm going to remove it. I'd like to build a proper roof over this "carport", but I'm not sure how to do it.

At this point, I'm open to any suggestions as to how best to keep the rain out. I'd like to eventually enclose it (at least on 3 sides), and I plan to pour a concrete pad, but none of this will be of much good without a solid roof. I've seen decks built on top of garages, and that looks good. However, I'm not sure how to do this without trapping moisture, which would cause the whole thing to rot in a few years---I want something that's going to last. Also, we have big redwoods and douglas firs (which means lots of pine needles), so the drainage needs to be good. Thanks.