Here is a possible template for a Guidebook page about an in-game Event. This is merely a suggestion, not a rule. You can use any part of it, all of it, or add your own ideas to it. To use it in its entirety, merely copy and paste it to an editor window in the appropriate Guidebook chapter.
(Give a brief summary of the event, including the approximate dates when it took place IC, major plot developments during and springing from the event, and characters who were most crucially involved.)
(Tell the story of the event from an IC perspective. Don't bother dividing events by threads, just explain what happened and when in a way that someone can read it and get a good idea of what happened without reading through every thread of the event)
(Make an unordered list of all the characters involved, including a separate list for Notable NPCs if there were enough of them to warrant it. If this was a sitewide event with too many characters to list, indicate that instead and note if any superteams or organized groups were involved.)
(Unlike other timelines, an Event Timeline is usually not best done with unordered lists, but rather with paragraphs with the thread title and link as the heading. Give the thread name and link, then take a few sentences to describe what happened in that particular thread, including characters involved, major developments, and whether it crossed over with any other thread. Try to list threads in order, and indicate if they happened simultaneously to other threads.)
(Most Events have consequences that stretch on beyond the conclusion of the Event itself. Describe the aftermath of the Event including significant plotlines that open or close, character relationships that were impacted, objects and places of significance damaged or destroyed, or anything else appropriate.)