To sign up for Yahoo! Wallet:

1. Visit the Yahoo! Wallet website.
2. Enter your Yahoo! ID (if you don't have one, you can get one by clicking Create an account at the bottom-right corner of the page).
3. Add a payment method by entering information about your credit card and billing address.
4. Click Continue.

You will see a screen confirming that your payment method was successfully added. The card will then be saved in your Yahoo! Wallet, and you can use it to securely purchase premium Yahoo! products and services.

Note: When you sign up for most premium or subscription services at Yahoo!, you are automatically prompted to enter your credit card and billing information, including phone number, into Yahoo! Wallet, so a separate sign-up is not needed. Some banks require both billing address and phone number to verify a credit card.