Using Xbox Live

• 1). Highlight the "Game Marketplace" from the Xbox 360 dashboard and select "Explore New Games."
  
  
• 2). Highlight "Add-Ons & Extras" from the list of options and select "Add-Ons."
  
  
• 3). Highlight "Titles A-Z" from the "Add-Ons" menu and select "B." Scroll down and select "Borderlands" from the list of games.
  
  
• 4). Scroll over to "Extras" from the list of options on the "Borderlands" page and select "The Underdome" from the list.
  
  
• 5). Select "Confirm Download" to purchase using the Microsoft Points tied to your account, or "Redeem Code" to use a promotional code for the add-on. Once completed, "Mad Moxxi's Underdome Riot" will automatically download and install on your Xbox 360 and be ready for access in "Borderlands."
  
  

Using The PlayStation Store

• 1). Select the "PlayStation Store" icon from the "PlayStation Network" section of the PS3 menu. If prompted, sign into the PlayStation Network using your account email and password.
  
  
• 2). Select "View All by Title" from the main store page. Choose "B" from the listed letters and select "Borderlands" from the list of games.
  
  
• 3). Select "Mad Moxxi's Underdome Riot" from the listed products on the Borderlands page. Choose "Add to Cart."
  
  
• 4). Select "View Cart" to review the content you wish to purchase. Choose "Proceed to Checkout" to move to the purchase confirmation screen. Select "Confirm Purchase" to buy the content using the funds in your "PlayStation Store Wallet."
  
  
• 5). Select "Download" once the purchase has been completed. Your PlayStation 3 will complete the download of "Mad Moxxi's Underdome Riot," and it will then appear under the "Game" heading of the PS3 menu. Select the newly downloaded content to install the add-on to your hard drive. Once complete, it will be ready for use in "Borderlands."
  
  

Using Steam

• 1). Launch the Steam client on your PC.
  
  
• 2). Type "Mad Moxxi's Underdome Riot" into the search field on the store's main page. Click on the add-on when it appears in the search results. Enter your birth date into Steam to confirm you are at least 17 years old, as "Borderlands" is rated "Mature."
  
  
• 3). Click "Add to Cart." You will automatically be taken to your Steam cart. Click "Purchase for Myself" to proceed to the Payment Information page.
  
  
• 4). Confirm your payment address and the method you wish to use as payment. Click the "Continue" button. If using PayPal, complete the payment login process. Once at the order confirmation screen, click "Purchase" to complete the transaction. Click "Next" to proceed through download preparation. Steam will download the add-on and automatically install the file into your "Borderlands" folder.