Paypal Instant Payment Notification ?

I received a Paypal Instant Payment Notification. I went to paypal web and read about notification validation guild,but couldnt understand. Where do i have to send the email to get the response from paypal like verified or Unvalid. Is that true that my paypal balance wont be credit before i send the email which i received somewhere to check the status first. Its my first time to deal with buyer via paypal, could someone help me out pls ?