A basic example.
Code:
<form method="post" action="send.php">
Your name:
<input type="text" name="name">
<p>
Your email:
<input type="text" name="address">
<p>
Subject:
<input type="text" name="subject">
<p>
Message:
<textarea cols="10" rows="5" name="message"></textarea>
<p>
<input type="submit" value="Send the email!">
</form>
You can add extra things to the INPUT fields like size (sets the size of the box) and MAXLENGTH (sets the maximum number of characters they can type into it).
That will send the four fields to the file send.php:
Code:
<?
$to = "youremail@whatever.com";
$subject = $_REQUEST['subject'];
$message = $_REQUEST['message'];
$headers .= $_REQUEST['address'];
$headers .= "From: $name <$address>\r\n";
mail( $to, $subject, $message, $headers );
?>
In the send.php you can add error checking, a result message, a page redirect, whatever. I think this form is probably about as simple as it gets.