Lucinda,

If you go to the Rock County Historical Society website on their "Contacts" page under "Marriage Lookup".

URL: http://www.rockcountyhistoricalsociety.org/contacts.shtml

You will find that the County Clerk is willing to do some free lookup for you and can you ask about how to obtain a copy of the marriage certificate if that is where they are married.

I hope this help.

Matt Friend