Open the Google Play Store app.

Tap the menu icon (three horizontal lines) on the top left.

Choose "Payment methods" from the menu.

Select the "Add payment method" button.

Pick a payment option: card, PayPal, or gift card.

Follow the instructions to enter payment details or redeem a gift card.

Review and tap "Save" or "Add".

Set a new payment method as default, if needed.

Use added payment methods for purchases.

Ensure sufficient funds for desired purchases.