Hi! I'll try to add this to our how-to-post tutorial, too. My screenshots might looks a bit different since I'm making them on a desktop computer (anyone can switch between mobile and desktop view, regardless of the device they are one. Just scroll all the way to the bottom and click "Desktop View", or "Mobile View")
First you click "Forums" and that loads the drop-down menu of all our forums. Chose the one you want, and then scroll to the bottom of the forum to click "New Topic." I'll also see if we can get a "New Topic" button at the top, as I
think that might be more user-friendly!