This forum is a place to post summaries/etc of IC events or as 'character journals', describing things they have experienced in their own words. Did your archenemy harass you in public again? Did something go down in town? Someone die? If so, why not make a topic about it? A few notes.
1) This is an in-character forum, so posts should be done in an in-character fashion. If it's a journal, write like your character would in their own journal. If it's an event summary, tell it from an outside perspective, or if your character is reporting the story (for example), post it like a news article.
2) The information in this forum is likely not public knowledge, unless specifically specified or obviously so. (The news article example would be public knowledge; character journals wouldn't be.) So no metagaming, as always.
3) If you're posting a journal, it would probably be ideal to post subsequent entries in the same topic, to save forum space.