So First you need to download the torrent
http://thepiratebay.se/torrent/6838457/Assassins_Creed_Revelations-SKIDROWmount the iso and install
Then open up the iso (go to computer, rightclick on it, choose open files explore)
find the crack, replace the files in the install directory
When you launch the game, it will ask for a patch download, let it download.
Then it will say do you wish to run the patch now?
Choose NO
it'll launch the game.
The next time you launch the game it will start downloading the patch again, just choose cancel it'll launch the game.