There are many sites which offers you to download games on them. but the best way is to get them through torrent.

1. first install a torrent supporting software like BitTorrent or utorrent

2. go to sites which offers them like those provided below. click on the links and they will direct you to torrent download.

3. the torrent downloading software will automatically start downloading.

4. now wait for the download to finish and viola you have your game