To add additional card in your Yahoo! Wallet, follow these steps:

1. Go the Yahoo! Wallet page.
2. Log in with your Yahoo! ID and password.
3. If you have an existing Yahoo! Wallet, you see the Payment Information page:
1. Click the "Add payment method" link on top of the page.
2. Add a payment method.
3. Click "Continue."
4. If you do not have an existing Yahoo! Wallet, you are taken directly to the Add payment method page.

You can also add a credit card to your Yahoo! Wallet during the purchase process.