I found the roles tab, but this does not give the user the rights I assigned to the role. If I give them the role at the course level, they have the proper rights, but to all forums. If I give them the role at the forum level, they do not gain the rights.
I looked at the rights that are defined for students for the site - everything is set to Inherit or Allow. I'm not sure if I've found a bug or just haven't been able to figure it out....