Here's a link to the Wisconsin Towns Association description of what a "town" is. It describes how it is governed, what services they provide and the unique voting powers in towns. It is written for advocates of towns, but still contains good information.
Here is a list of towns in Dane County, with a link to their websites:
Town of Medina - Town Hall: 634 State Road 19, Marshall, Mailing Address: P O Box 37, Marshall 53559 Phone: 655-3030
Town of York - 796 York Center Road, Marshall 53559, Mailing Address: 398 Sun Prairie Rd, Waterloo 53594 Clerk's Phone: 516-0828