Senting email with php

I am using a contact form in my website and I need to sent the details to a particular email in the same server as email.

My hosting provider shared the below code ,but I don’t know how and where to use this.
Please help.

<?

$mailto=”[email protected]”;
$pcount=0;
$gcount=0;
$subject = “Mail from Enquiry Form”;

$from=”[email protected]”;
while (list($key,$val)=each($_POST))
{
$pstr = $pstr.”$key : $val \n “;
++$pcount;

}
while (list($key,$val)=each($_GET))
{
$gstr = $gstr.”$key : $val \n “;
++$gcount;

}
if ($pcount > $gcount)
{
$message_body=$pstr;
mail($mailto,$subject,$message_body,”From:”.$from);
echo “Mail has been sent”;
}
else
{
$message_body=$gstr;
mail($mailto,$subject,$message_body,”From:”.$from);
echo “Mail has been sent”;
}
?>