There is nothing wrong with Chris' answer, but I'd like to add two things.
First, (c) (from the title of the question) or more accurately ©, is copyright, which is not used with company or service names. So you would never write Facebook©, although if appropriate you may write © Facebook.
Second, ® - as I am sure you are aware, but adding it for completeness, trademarks can be registered with other bodies too, particularly outside of the US. For example, in Sweden, you would register with the Patent and Trademark Office (PRV). For EU-wide protection, the European Patent Office should be a good place to start. And so on.