Have you tried calling Adobe Customer service? They can deactivate one of your installations so that you can install and run on a new system. And perhaps they can help with your other problem, or send you to a tech support rep who can.
With regard to your use of DW, I'd strongly suggest that you take advantage of this downtime by learning as much HTML and CSS as you can absorb. Multiple sittings would be helpful. The more you know about those two, the easier DW will be for you when you eventually get it going.
Here are some tutorial sites that may be helpful -