The link did help! It showed that you have a MIXED application at the top level and clearly don't want people posting at the top level.
You should remove the "Create_topic" and "Reply" permissions for all groups - including "Administrators" from the top level. You then need to add those permissions on each and every sub-forum where you do want members of specific groups to post or reply.
The effect of these two changes will be that when someone clicks the general "New Topic" link they will be presented with a list of sub-forums in which they have permission to post and they will have to select one before they see the message composition screen.
Be aware that forum administrators can find they get spam posters if they allow "Anyone" to post, so you might find it prudent only to allow "Registered" users to post and reply, removing the "Create_topic" and "Reply" permissions from "Anyone".
(As a personal preference I would rename your first sub-forum to something like "Introduce Yourself". Because the tool-tip that appears when you hover over a sub-forum "New Topic" link echoes the name of the sub-forum, the question marks and down arrows you currently have, look a little out of place.)
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.