My b2evolution Version: 2.x

I'm sure that this question has been asked here before, so I apologize for any duplication. I think that I may not be searching with the right words. :-/

I would like to password protect Blog B, so that only certain users can post or view it's content, while ALL registered users can post to Blog A, and everyone out on the Web can view Blog A (but not post)

Hope this makes sense.