I couldn't find a way to configure a different image at the side of each forum. is that possible? How to do it?
But his plugin you need to add the icon that shows if there is new messages or it is closed, is there a way to just add an image at the side of each forum?
You mean on-off images? If so, just make the corresponding images and upload each as on.gif, off.gif, and offlock.gif in the theme's directory. I suggest uploading as .gifs as to not disrupt the integrity of the board.