Forums linked to a certain scene can be found in the "Forums" box within each scene.  

In order to enter a forum, you have to click on its name. Here you can find the forum description, a textbox to write a new comment and the previous post in the forum. 

If there are multiple pages in a forum, you can reach them by clicking on the "Previous" and "Next" buttons under the list of forum posts. 

If you liked someone's post, you can show this to them by clicking "Like".