Amnesia Collection

- go to the store page of Amnesia The Dark Descent
http://store.steampowered.com/app/57300/Amnesia_The_Dark_Descent/
- Or just search for Amnesia on steam
- http://store.steampowered.com/search/?term=Amnesia
- Scroll down (its under the Add to Cart button)
- Click on Install Game
- Thats it, the games are added to your account forever

Screenshot because some people have a problem finding the button
https://i.imgur.com/fdZzkgu.png