The Sandbox exists so that you can practice editing or formatting (see Editing help) without changing any serious content. Feel free to try wiki editing out here first. You won't hurt anything by editing this sandbox. It can easily be put back the way it was so that other people can practice here, too.
There is a tutorial on the Central (coordinating) Fandom that will step you through more of the things you can do. Wiki allow for rather complicated formatting. It can look overwhelming when you begin, but don't let it worry you. Just start with the basics... enter some text, and learn the other pieces as you go. Your content contributions are welcome and important. The wiki is a collaborative effort and others can help with formatting and other improvements.
Best wishes!