I have installed a test community forum on my webserver just fine and I was testing it out by registering a couple accounts which worked fine. After they complete the registration, they are allowed to comment anywhere just fine. Unfortunately, when I try to start a topic with the accounts, I get a Permission denied error. I can’t find the where in the settings to enable newly registered users to automatically be able to create topics after they register without having to manually set them as contributors. Also, I would like to find a way that (if I have a blog and forum, when they register for one, they can start topics on both. Any help?
Reported on Movable Type 4.2

I pretty much want it to work like this forum does btw. People register, and then right off the bat, can create post
Hey, I had the same problem and found the solution.
Go to System Overview -> Users -> Permissions, then select Grant permission to a user.
Select (newly created user), click continue.
Select Author as the Role, click continue.
Select your Blog/Forum from the list and click continue.
From then on new users when they sign up will automatically be given the Author status, which is what is needed to Start a Topic.
Hey, after almost an hour of digging I actually found the answer and was just about to come here to post it. Thanks for the information too though. Hopefully it saves someone else a headache.
"From then on new users when they sign up will automatically be given the Author status".. but what a bout the author limit? According to license it should be only 5 authors in MT installation.