How to play sims 3 with no disk? (torrent/mounting problems!!)?

okay so i downloaded the original sims 3 game torrent. i also downloaded PowerISO which is a mounting tool like daemon tools. i mounted the download (i think) and when i try to launch the game, a pop up comes up and says, "The set up has detected that no version of The Sims 3 is installed. This update requires that a preivious version of the application be installed." what does that mean and how can i fix it?? i just REALLY want to play!