First, instantiate client with your username and password
$client = new LitmusClient('username', 'password');
Call resource needed. Check services classes to see what endpoints methods are available.
example: get list of support email via instant enndpoint $result = $client->instant->getSupportedEmailClients();
You can pass array url parameters or post parameters when endpoints allow you to. Yous should refer to official litmus configuration to know availiable options $params['query'] = [array of url params] $params['post'] = [array of post params]