In each of the 280 Empik and Papiernik by Empik stores in Poland, you can pay with cash, credit/debit card, gift card, or Sodexo bonds.
In case of purchase at the stationary stores, it is not possible to book tickets online in advance. You can choose and buy them directly at the cash register. The store employees will help you find the event you are interested in, pick the right ticket type, and (in some cases) choose specific seats. The staff will also answer any questions you might have about the event.