This is getting into a lot of legal stuff, but here goes. I believe that most of the time all that you have to do is say that the items are copyrighted to you, and they should be. I'm not completely familiar with copyright law, but I think once you create something, then it is technically copyrighted so that no one else can use it without your permission. I would do a little Google search on copyright law, but from what I know, you just need to physically put on the item that it is copyrighted.