To send an email in php use the mail function

bool mail ( string $to , string $subject , string $message [, string $additional_headers [, string $additional_parameters ]] )

Working example

    $to = "in**@so********.com";
    $from_header = "From: auto@" . $_SERVER['HTTP_HOST'];    //Uses host domain name
    //$from_header = "From: " . $Email;
    $subject = "MY EMAIL SUBJECT";
    $body = "Some text";
    $body .= "Some more text";
    if (mail($to, $subject, $body, $from_header))
    {
          echo("Message successfully sent!<br />");
    }
    else
    {
          echo("Message delivery failed...<br />");
    }

PHPMailer

Great when you want to send email via a SMTP server (e.g. googlemail), attach files to emails, etc
Download from http://phpmailer.worxware.com/
Copy class.phpmailer.php, class.pop3.php and class.smtp.php into your site (e.g. in a folder called phpmailer) and use one of their example files as the basis to send email.