Kate Middleton and Prince William say "I do" tomorrow morning! The whole world has been buzzing about their fairy-tale romance for months, but what can you expect once the wedding kicks off? We're walking you through it, step by step. Get the scoop on everything from Kate's dress to the celebrity guests — plus where you can watch the special ceremony. We'll be giving you all the royal wedding action live on PopSugar during, too, including a live stream of the ceremony and editor commentary of all the fun!