Well Dreamweaver comes with a helpfile that will explain it's features and how to use them, so if there is somethign specific that you do not understand you can search the help file. I would suggest that you learn at least basic HTML too. Dreamweaver writes code for you but sometimes you might need to tweak it and other times you will need to know how the code works in order to make things work properly. Dreamweaver is a great tool and it speeds up the production of webpages, but it isn't perfect and it helps to know the code.
As mentioned above,
http://www.w3schools.com/ is an excelent place to learn HTML and other web languages.
I would suggest that you just sort of dive into the program and mess around. See what you come up with. Exploring and familiarizing yourself to the application is important when learning any new program.
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