Hi Hubberbubber. Sorry, I am not usually used to answering questions -- usually I am the one asking!
To copyright any piece of work (online or print) you simply need to claim it!
Insert the "c in a circle" symbol and put your name or your username. You can put the year or you don't have to.
But honestly, even without the formal "c in a circle" symbol your work is protected.
It's similar to simply putting "tm" or "sm" on your brand. You just put it on and claim it. It's only if you want to officially trademark "R in a circle" that you have to file with the government.
I hope I have answered your question. This would make a good hub subject!