Step 1: Download the game downloader.
Step 2: Run it. (It will start downloading the game install to a default folder. This folder can be changed from the options menu.)
Step 3: After it finishes downloading run the Install. 2 types of installation should show up: Standard and Personalized. First will install the game in the default system drive in 'program files' second lets you choose where to install the game. After choosing wait till it finishes.
Step 4: Run the game.
Game updates are downloaded via a peer-to-peer system (at least on the us version) so the speed may vary depending on the zone and internet provider of the seeders.