I can't send Email in PHP

Question

Warning: mail(): Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in C:\Users...

$from = 'myemail@gmail.com';
$to = 'clientemail@gmail.com';
$subject = "welcome";
$headers = 'From: '.$from;
$message = 'Hello!';

        // Sending email
        if(mail($to, $subject, $message, $headers))
        {
            echo 'Your mail has been sent successfully.';
        } else
        {
            echo 'Unable to send email. Please try again.';
        }