Minimum:
OS: Windows Vista / 7 / 8 / 10 64 bit (32 bit NOT supported!)
Processor: 3.0 Ghz Intel Core i3 or equivalent
Memory: 4 GB RAM
Graphics: 1 GB nVidia Geforce GT460 or equivalent
DirectX: Version 9.0c
Storage: 500 MB available space
Sound Card: DirectX 9 Compatible Audio
Go to: http://store.steampowered.com/ and download STEAM client
Click "Install Steam" (from the upper right corner)
Install and start application, login with your Account name and Password (create one if you don't have).
Please follow these instructions to activate a new retail purchase on Steam:
Launch Steam and log into your Steam account.
Click the Games Menu.
Choose Activate a Product on Steam...
Follow the onscreen instructions to complete the process.
After successful code verification go to the "MY GAMES" tab and start downloading.