A copyright is created automatically when you create a unique work, whether that’s a piece of art, a design, a website, a photo, etc. However, if you want to prevent anyone else from using or distributing the copyrighted work, you will have to register that piece.
A registered copyright protects original work of authorship. This would include paintings, photography, etc. While you automatically have a copyright upon finishing a creative work, you’ll want to register the copyright if you want to be able to pursue infringement claims if someone copies it. You should also add a copyright notice to the footer of your website! (e.g. © 2021)
You must also register the copyright 3 months from the creation of the work, or you can only pursue infringement claims for events that happen after you register.