Can I place the copyright tag on my webpage without having to sign up for anything?

[bcnu]

In the USA, and over 160 other countries, there is absolutely no obligation to "sign up", let alone pay for any copyright of your own creative works of authorship. Copyright registration in the USA is only required as part of filing a federal lawsuit. You should put your copyright notice on ANYTHING you publish, to remind people who owns the rights to it.

Your copyright ownership is free and automatic from the moment your creative work was put into any tangible form (bits in computer memory, sketch on paper, snapshots in camera memory, etc).

On the other hand, you should be careful to distinguish YOUR works from those of others, if your webpage contains content obtained from others, because they own their copyrights and you would (a) need permission to us it and (b) could get into trouble for putting your copyright notice on the page without proper acknowledgement of their ownership.

For instance, this answer and your question are covered under my copyright and your copyright, respectively, but we have each licensed certain distribution rights to Yahoo!Answers, so they can put copyright notice on the page and would NOT be appearing to claim to be the owners of our works.