It’s easy. Put this form in you html page:
<form method="post" action="mail.php">
<textarea rows="4" name="txt" cols="50"></textarea>
<br><br>
<input type="submit" value="Submit" name="b1">
<input type="reset" value="Reset" name="b2">
</form>
and create file mail.php:
<?
if (@mail("you@mail.com", "Subject", "$txt")) { echo "Mail send"; } else { echo "Error"; }
?>
Do not forget to replace you@mail.com with you mail address.