SMF For Free Support Forum

Forum Url: http://lewportalumni.com.smfforfree.com
I have added a post that reads "guest book" to my site.  How do I allow guests to sign it?  Or can you recommend a guest book to incorporate into the site?

Create a Board called "Guest Book" and give Guests access to it.   
(You can not give them access to just one thread in a Board. )

You'ld need to use Permissions by Board to give them the ability to reply to that Board
This Guide explains Permissions by Board.
Admin CP Permissions Section Guide
       

If you want a Guestbook - Efreeguestbooks works good.. you could signup with them and use the link for the Guestbook that they give you as a link via Manage Styles > Custom tabs 

http://www.efreeguestbooks.com/support.html