Things You'll Need
Instructions
Xbox.com
Log in to your Windows Live account. Enter your email address and password, then click "Sign In."
Select "Microsoft Points" from the toolbar. A new page will open showing you your account balance.
Select how many points you want to purchase. As of summer 2011, 400 Microsoft Points cost $4.99, 800 Microsoft Points cost $9.99, 1,600 Microsoft Points cost $19.99, 4,000 Microsoft Points cost $49.99 and 6,000 Microsoft Points cost $74.99. Click "Next" once you've made your selection.
Enter your billing information, like your full name, address and phone number, then press "Next."
Enter your credit card information, including your card number, expiration date and security code found on the back of the card. Press "Submit" to complete the purchase.
Xbox Marketplace
Turn on your Xbox and sign in to your account. Enter your email address and subscription number. This subscription service is required to access Xbox Live.
Press the Xbox Guide button on the controller to access the main menu. Select the "Settings" tab from the menu.
Scroll down and select "Account Management." Press the "Select" button.
Select "Add Microsoft Points" and select how many points you want to purchase. Your saved credit card account will be billed with the amount of your purchase.