how do i use apple card?

You will only get a physical (titanium) card if you request one. See: How to request or replace a titanium Apple Card - Apple Support

For information on using the Apple Card (with or without a physical card) see: How to make purchases with Apple Card - Apple Support

Welcome to the Apple Card! You can pay with Apple Card anywhere Apple Pay is accepted, and use the titanium card or your virtual card number anywhere Mastercard is accepted.

You can request a titanium card here ⇢ How to request a titanium Apple Card - Apple Support

Learn ⇢ How to make purchases with Apple Card - Apple Support

-Zachyy ✌️