In Drupal Commerce, there is no way how to add new payment methods via user interface, you just need to write a module. So I did. All it does is that people will be able to pick "V hotovosti pri dobierke" in their order process.
- Drupal Commerce
Copy the module to /sites/all/modules folder and enable via user administration
You need to enable the newly created payment method in user interface on /admin/commerce/config/payment-methods