This is a dumb question but I cant figure out how to place community lots
The stupid guide is not good enough.
Do I have to place a empty plot first and then place it or what?

If you cannot place a community lot from the bin to an empty lot, there's probably something on that lot and you need to demolish it first. You may need to also change the lot assigment. If you don't have any empty lots available, then you can add new empty lots with the lot tool. Just remember, that the lot tool is broken and adding new empty lots to your world will break the routing and cause routing issues/lag. The more added new lots with that tool, the bigger the problem.