After you have installed the Steam Client, created a Steam account and logged into the Steam Client using that Steam account you can activate your games.
Once you have activated a game in a Steam account it cannot be activated in another Steam account, but you can login using the same Steam account on more than one computer then download the same game to each computer.
To activate a game in a Steam account:
  1. At the main Steam window:

    Either:
  • In the lower left corner of the Steam window, click on "+ ADD A GAME..." and then on "Activate a Product on Steam...":
  • In the upper left corner of the Steam window (above STORE, LIBRARY, COMMUNITY) select the "Games, Activate a Product on Steam..." menu:
  • Click the "NEXT" button to continue:
  • Review the Steam Subscriber Agreement, then click the "I AGREE" button:
  • Enter the Steam key you received from Bundle Stars exactly as shown by Bundle Stars (if possible, use copy and paste to avoid typing mistakes), then click the "NEXT" button:
  • If you don't already have the game being activated and you have entered the key correctly you should now see the following page, click the "PRINT RECEIPT" button if you want a receipt for this activation, then click the "NEXT" button:
  • Steam will assume you want to download and install the just activated game immediately and will provide some information about that download process.
    If you want to download the game now, click the "NEXT" button, otherwise click the "CANCEL" button:
  • Steam can optionally create shortcuts to play the game on your computer desktop or in the "Start" menu to make it easier for you to start the game.
    If you would like Steam to create these shortcuts tick the check boxes, then click the "NEXT" button:
  • Steam will prepare to download the game, when the download starts the screen will automatically advance:
  • You can click the "Manage Downloads" to view the download progress (or to pause/stop the download), click the "FINISH" button to close the activate game wizard:
    • Once a game is downloaded and installed you can start it via your Steam Library of Games by selecting the game in the list then click the "PLAY" button:
    Alternatively, if you created them during the download and install stage, you can use the game shortcuts on your computer desktop or in the "Start" menu to start the game.