Use of multiple menus in Edu-clean

Okay, I've the Membership plugin up and running ... my site looks like I want it to (finally!) with one exception:

I need to have "Visitors" see a different menu other than what "Registered Users" see. I have enabled multiple menu support in my theme and defined the two menus, but can't figure out how to segregate the users so that the correct menu will be shown at the right time.

Help?