To add your Cash App to Apple Pay, you need to add your Cash App Card (debit card) to your Apple Wallet. Here are the steps:

1. Open the Cash App on your iPhone.
2. Tap the "Cash Card" tab on the main screen (it looks like a little credit card).
3. Tap on your Cash Card image.
4. Select "Add Card to Apple Pay."
5. A screen will pop up showing your Cash Card details. Tap your device’s name to start adding the card.
6. Agree to the terms and conditions.
7. Once completed, you will get a notification that your Cash Card has been added to your Apple Wallet.
8. You can then set the Cash Card as your default card in Apple Pay or choose "Not Now"

Alternatively, you can add the Cash App Card via the Apple Wallet app:

• Open Apple Wallet.
• Tap the "+" sign to add a new card.
• Scan your Cash App Card or enter the card details manually.
• Verify your card via text message or phone call.
• Once verified, the card will appear in your Apple Wallet

Note that Apple Pay itself doesn't hold cash but uses linked cards like your Cash App Card to make payments. If you want to add funds to Apple Cash (Apple's prepaid debit card), you can do so separately via the Wallet app, but that is different from linking your Cash App Card to Apple Pay

. In summary, to use Cash App funds with Apple Pay, add your Cash App Card to Apple Wallet following the steps above. Then you can pay anywhere Apple Pay is accepted using your Cash App balance through the linked card