它是right here in the codex.

这是示例代码，显示了如何创建新用户：

$user_id = username_exists( $user_name );
if ( !$user_id and email_exists($user_email) == false ) {
    $random_password = wp_generate_password( $length=12, $include_standard_special_chars=false );
    $user_id = wp_create_user( $user_name, $random_password, $user_email );
} else {
    $random_password = __(\'User already exists.  Password inherited.\');
}

在这里，another wrapper version with more functionality.

$website = "http://example.com";
$userdata = array(
    \'user_login\'  =>  \'login_name\',
    \'user_url\'    =>  $website,
    \'user_pass\'   =>  NULL  // When creating an user, `user_pass` is expected.
);

$user_id = wp_insert_user( $userdata ) ;

//On success
if ( ! is_wp_error( $user_id ) ) {
    echo "User created : ". $user_id;
}

关于构造表单、与mailchip集成等的部分-如果您需要查看代码示例以涵盖问题的这一部分，最好在不同的问题中提问。