To use Google Pay, first download the app and link your bank account, debit card, or credit card. For online payments, select Google Pay at checkout and confirm the payment using your phone’s security (PIN, fingerprint, or face unlock). For in-store payments, open Google Pay and tap your phone on the NFC-enabled payment terminal at the store. The payment will be processed instantly, making transactions fast, secure, and convenient without needing to carry cash or cards.