1. Open the Microsoft Store and click the "Login" button in the upper right corner to log in to the Microsoft account.

2. On the page of Microsoft Store, find and click the "Account" option.

3. On the account page, find and click the "Payment and Billing" option.

4. On the payment and billing page, find and click the "Add payment method" option.

5. On the page of adding payment method, select options such as "credit card or debit card" or "PayPal" and fill in personal data address and related information.