You don't have to put together anything too formal (unless you want to), and any topics related to children's/YA literature, and/or blogging about said literature, are welcome. From the official post:
Repeat visits to past topics are welcome alongside new ideas. A few thoughts—we’ve never talked specifically about historical fiction (is there such a thing as “getting it right?”) or religion (books written for a specific audience, books specifically addressing social and cultural topics related to religion). There’s always room for conversations about class, race, disability, sex. gender, politics, and pictures!Contact the organizers by August 1 with your ideas, and check out this post for more details.