Unscrew screw (righty tighty/ lefty loosey). Take out old one. Put new one so it fits over screw hole. Screw in new one.
Here are a bunch of ideas on Hometalk - maybe one of these will inspire you :) - https://www.hometalk.com/search/posts?filter=switch%20plates
You can always cover it with wallpaper, paint it, use a Sharpie to decorate it, Mod Podge tissue paper on it, or add a frame to it.