This is a very interesting area, because the copyright over the code of a site is different to the code of a program. You can't copyright the HTML tags, because they're in the public domain, and it's hard to protect the order in which you used those tags because it's unlikely that what you've done is original. The actual look of the website isn't protected because it's rendered by the web browser, and there are many different ways of achieving the same look. What is interesting, is that if anything, a website has more in common with industrial design rights rather than copyright, but design rights can only apply to 3-dimensional objects. Basically it's a very grey area, and there haven't been any cases (as far as I'm aware) to test under what area and exactly how a website's code falls under copyright law.
What is 100% copyrightable though are your original images that you have created. This is granted automatically when you create them.