As hash already said, your work is automatically copyrighted the instant you create it. That is, if your country is a signatory of the Berne Convention, which it likely is. The existence of that Internet changes none of that. The length of the copyright has no relation to the length of the registration of your domain name.
Before the Berne convention, works had to usually be registered with the country's copyright office for countries you wanted copyright protection in, and you had to display a copyright notice (if in the US). If you work was created after that date (it varies with the country that you are in), then you don't have to worry about it. Given the recent age of the Internet (and thus websites), you don't have to worry about it.
If you are in the US, registering for copyright protection with the copyright office offers advantages, such as the ability to sue for statuary damages (sue without having to prove the monetary damages, i.e. sue purely based on the act of infringement).