NOTE: To use forums you need to enable it in settings. Go to Configuration -> Settings -> Forum settings and check the "Forum enabled" box.
To add new topic you need to enter specified Forum group and click "New topic".
From the 3.90 version you are able to vote for added posts. You can't vote for your own post, you are able to vote only once per post and you can set limit of votes per day in the Forums Setttings.