What i understand is you want to send the contents in textbox in an email.
For this you need to submit your form to another php page and then send email. See the following code

Now on mail.php

If SMTP settings are OK in php.ini, your email will be recieved at $strTo from $strFrom.

here all you have to do is
require_once(’whateveryounamemyfile’);
$MyMail=new MyMail($To=”Email address”, $Subject=”Subject”, $Msg=Message or body, $From=”From email address”, $ReplyTo=”reply to email address.or use from email address”);

$MyMail=new MyMail($To=”Email address”, $Subject=”Subject”, $Msg=Message or body, $From=”From email address”, $ReplyTo=”reply to email address.or use from email address”);