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.