1. Include the required PHP file from the paymill PHP library. For example via:

   require_once 'lib/Services/Paymill/Transactions.php';
   

2. Instantiate the class, for example the Services_Paymill_Transactions class, with the following parameters:

   $apiKey: First parameter is always your private API (test) Key

   $apiEndpoint: Second parameter is to configure the API Endpoint (with ending /), e.g. "https://api.paymill.de/v1/"

   $transactionsObject = new Services_Paymill_Transactions($apiKey, $apiEndpoint);
   

3. Make the appropriate call on the class instance. For additional parameters please refer to the API-Reference:

   $transactionsObject->create($params);
   

For further information, please refer to our official PHP library reference: http://paymill.de/doumentation/referenz/api-referenz/