If you need to enroll in online paperless bill for Walmart Rewards Mastercard, you can do so here:
Walmart Rewards Mastercard Login
If you haven't done so, you can enroll by inputting your card number and your name on card. Follow the registration process. Once done you can login and click on "Electronic letters and statement". There you can download the electronic version of the Walmart credit card bill. In order to pay for the amount indicated in the Walmart Mastercard bill, you will need to pay using your Financial Bank such as Td bank, RBC, BMO or CIBC and other banks, You need to have already setup the payee as Walmart Mastercard with your credit card number as the account number (In your online banking website).
After paying your bill, the changes won't be reflected immediately in your Walmart Mastercard online account. It will take several days before you will see your bill balance go to zero.