To make the site simpler for new users, the third level forums are hidden. But that doesn't mean you can't get at them. There are several ways:
First way: Use the Forums Menu item to find the forum.
Click on the "Forums" menu item at the top. Move the mouse over to the Image Discussions arrow, Click and hold amd move the mouse pointer down over the next set of forums. Do the same thing for the next arrow. That should bring up all the third level forums. Click on one of those to open it up.
Another way: Click on Image Discussions to show all the threads in that forum. Each thread shows where it sits. If you click on one of the little buttons, it will take you to that forum. The picture shows an example:
Third way: From the web site (landing page), click on any of the forum shortcuts to be taken there:
