Well, it's not project management software so there are no rules or stages. You add a task to a board. Then you can comment on that task, move it to another board, share it with someone else, etc. I'm pretty sure their website has all of this stuff answered way better than some random reply you'd get here.
Can you set rules for items moving to the next stage?
Does anyone use this in work to manage their projects? (As part of a team and not as part of a team)