Beerhead, this can be kind of a complex operation. But after you buy a game, you should receive an email with download instructions. Read over that first. Here are some basic steps, but it's difficult to explain because the download process could vary based on which game it is.
In order to download a game you purchased from Amazon, you'll need to know where to find your game and you'll probably need to install the Game Downloader if you haven't already.
1. If you already have Amazon's Games and Software Downloader installed, find the shortcut to it and get it started.
2. To find your Game library, look at the top middle-right side of Amazon's webpage under Account. If you hover your mouse over that, a menu will open up. Click on the Your Games and Software library link.
3. Your listed game will have a button that says Download by it. Click on that to get started. If your purchase includes a product key, click Show Product Keys under the title in Your Games & Software Library. You also may need to select which computer you wish to download the game to from the dropdown list near the Download button.
4. If you've already opened the Downloader, the download should start by itself. Otherwise, you'll need to click on the link to install the Downloader first. After it installs, the game download will start. On some of the games, you may get an automatic option to download the installer just by clicking the game Download button. You'll see a browser option to run this installer. Do so, then start the download that way.
Here's a link with details:Installing the Amazon Downloader and a Game
5. Once the game is downloaded, you should see a window with the button to Install the game. Once installed and the game starts and authenticates itself, you may need to put in the Product Keys found in your Games Library.