Instructions
Start the Avatar Editor by selecting the "Customize Avatar" option from the "My Xbox" menu.
Enter the "Marketplace" tab to browse through the selection of downloadable avatar props and clothing.
Select "Game Styles" and scroll through the list of Xbox 360 titles until you find "Snoopy Flying Ace."
Choose from the Peanuts-themed avatar items and download your favorites. All of these downloads are priced from 80 to 240 Microsoft Points. Pay for the points with the credit card associated with your Xbox Live account.
Return to the "Change My Style" tab in the Avatar Editor and equip your avatar with the items you downloaded. Depending on what you downloaded, your downloaded content will appear in either "Headwear," "Props" or "Tops."
Use the "Save and Exit" tab to return to the "My Xbox" menu while saving all changes to your avatar character.