Most email programs provide you with two easy ways to create new messages by using other messages you have received: reply and forward.
Replying means sending a message back to someone from whom you have received a message, to respond to that message. Forwarding is passing a copy of a message you've received to a third party, either because you want to share the message's content with the third party or because you believe that, although the message was originally sent to you, the third party is a more appropriate recipient for it.