I am stuck at "Create a Guest Administrator and deactivate it." I've tried so many different things, but I don't feel the tutorial covers it very well. Perhaps I was supposed to remember it from a previous tutorial, but I must have forgotten. Can someone walk me through it?

I am stuck at "Create a Guest Administrator and deactivate it." I've tried so many different things, but I don't feel the tutorial covers it very well. Perhaps I was supposed to remember it from a previous tutorial, but I must have forgotten. Can someone walk me through it?