It works in the same way as adding a new entry and has mandatory fields for user registration.

$item = array(
  'group_id' => 4, //4 - User group ID
  'firstname' => 'Сергей',
  'lastname' => 'Харчишин',
  'username' => 'admin',
  'email' => '',
  'password' => '', //If not specified, it will be generated automatically.

$params = array(
  'key' => 'XgDXFsTbNRkMpRq81bBrmRAf56i5oS0oN9bp4jLH',  
  'username' => 'manager',
  'password' => 'manager',
  'action' => 'insert',
  'entity_id' => 1,
  'notify' =>true, //A notification will be sent to the user.
  'login_url' => 'http://localhost/rukovoditel/index.php',
  'items' => $item ,
$ch = curl_init('http://localhost/rukovoditel/api/rest.php');
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($params));
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);			
$result = curl_exec($ch);

  $result = json_decode($result,true);


Field Description
entity_id Must be 1
notify To send a notification to the user's mail (true/false)
login_url The login link is added to the user notification.
items An array of records, including the fields of the record.

field_X - the field to add, where X is the field ID. The field ID can be found on the "Field Configuration" page. This field takes a value as a string.

Required field Description
group_id Group ID for the user.
You can find out on the "User groups" page.
firstname First Name
lastname Last Name
username Username
email Email
password Password. Can be left blank, will be generated automatically.