Do I have to use copyright notice?

For any work that you have created or published after March 1, 1989, you do not have to include a copyright notice. However, it is a good idea to do so anyway, because if you do not include a copyright notice and later file a lawsuit for copyright infringement, the other party can argue that they were innocent because they did not know the work was copyrighted. They cannot make this innocent infringer argument if the work had a copyright notice.