use this
<?php
$to = "mymail@gmail.com";
$from = "mymail@gmail.com";
$subject = "Testing mail";
$header = "MIME-Version: 1.0\r\n";
$header .= "Content-Type: text/html; charset=ISO-8859-1\r\n";
$header .= "From:" . $from;
$message = "<html><body><head></head>";
$message .= "<h1>Hello, World!</h1>";
$message .= "</body></html>";
if(mail($to,$subject,$message,$headers)){
echo "Mail Sent.";
} else {
echo 'failed';
}
?>