1) use proper title
2) stop attempting to write php or html when you have absolutely, ABSOLUTELY no basic knowledge
form action basically tells the browser on what page should it send what you've posted, "/" if the thing that handles your form is on the same page "/mail.php" if it's in mail.php for example, along action you *should* define method, post or get.
also you can not use shorttag at form, where would the inputs be?
then why would you wrap $var in quotes at all? also mail() works only on server that has mail server installed and I'm sure that it won't work with just "to", not withough warnings or some poop.