Restricting who can read and write posts

How can I set my forum to prevent anyone from reading or writing on the forum without first logging in?

Also, is it possible to prevent certain groups from adding avatars or banners?

Ap==>General==>Categories and Forums==>Click the little icon with the green arrow and red X, near the designated topic==>Unmark View and Read for guests.

That should do it but just in case unmark write and reply for guests as well

Thanks for that but is there not a single setting that will handle all posts/topics?

I am a member of a forum that is php based where the first page that comes up is the login one and you can't go any further without a correct login or going to the registration page. Does this happen if all topics are marked as you suggested?

Yes, that's because all guests or restricted from the Forum, if you change it for guests to view, they will be able to see it, but if they try posting it'll take them to a log in page