Adding the payment module
There are two ways of adding PayZen payment modules:
The first method consists in adding the payment module via the Drupal_Commerce Back Office.
From the administration panel of your store, go to the Modules menu and click on Install a new module.
Then click the Choose File button and load the payment module.
The second method consists in copying the module via FTP. To do this, copy the payzen commerce folder into the /sites/all/modules folder of your website.