every fest is different, but generally you post to a collection that is hidden until the "fic reveals" day. some fests spread out the fic reveals over multiple days but they make all the fics visible to readers. every fic is anonymous so readers can "guess" each author. typically there's a small break after the fics have been posted, then they reveal all the authors. they do this through the collection + posts on twt :3 that's a very basic run down, but hopefully it makes sense