use Stripe\Stripe;
$stripe = new Stripe("your_api_key");

use Stripe\Request\Customers\CreateCustomerRequest;

// create a customer
$request = new CreateCustomerRequest();
$request->setEmail("[email protected]")->setDescription("A customer!");
$customer = $stripe->customers()->createCustomer($request);
// get the newly-created customer's id
$customerId = $customer->getId();

// retrieve a customer
$customer = $stripe->customers()->getCustomer("customer_id");