REMOVE TWO WASHER LIKE NUTS ON TWO OF THE THREADED BOLTS THAT YOU ORIGINALLY REMOVED THE LUGS FROM TO REMOVE THE WHEEL. Then tap the drum around the perimeter with a hammer to loosen that drum and pull it off, little by little you will get it off. You could use a little WD40 to help get it loose, if it is really stuck on. Good Luck it is not that difficult.
Yo Boom Bang, June 2007