How can I let users create accounts to log in?

I just installed a new forum section on my website. It says I have version 2.2.3. http://www.utahstories.com/forums/forum/readers-forum/

I can’t figure out how to enable a way for users to log in so they can create forum accounts. All it says is that “you must log in to create topics” but it doesn’t give any way to do this. Anyone know how?