Hi MyBlood,
I hope the day is going well 🌻!
I'm reading your question and I'm asking what do you mean with the question about how pin the first post but not the whole forum (maybe discussion?).
When you create a topic the content of the topic will be the first message in the discussion.
If you want to pin a discussion then you can do in the reply button of the first topic content where you find the pin option.
If you want hide or show a specific tag from all discussion you can manage this going in the admin tag extension then when you edit a tag you can choose to hide a tag from all discussion by checking the relative checkbox.
If you are looking to pin a specific comment in the discussion, this can maybe possible, at the moment, using the extension best answer.
I hope this can help you.
