Exemplo autenticação http basic

auth.php

$login = 'hjk3kj3h534h53kj4j345';
$password = '3k45jh3k4j5h3k4j5h34kh5k34';
$url = 'https://apic1.hml.stelo.com.br/';
$encode = base64_encode("$login:$password");


$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_TIMEOUT, 30); //timeout after 30 seconds
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_HTTPHEADER,
    array(
        "Authorization: Basic " . $encode)
    ));
$status_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);   //get status code
$result=curl_exec ($ch);
curl_close ($ch);
echo $result;
echo $status_code;