Or just do:
[form.html]
``<html><body><h1>Post here:</h1><form name="theform" action="post.php" method="post"><textarea name="comment" placeholder="Post a comment here" rows="8" cols="64"></textarea> <input type="submit" name="submit" value="Reply" /></form></body></html>
[post.php]
``<?php $conn = mysql_connect('localhost','root',''); $db = mysql_select_db('wakaba_beta',$conn);
$mysql_query("INSERT INTO wakaba_beta.posts (name,comment) VALUES ('Anonymous','".mysql_real_escape_string($_POST['comment'])."');
mysql_close();
header('location:posts.html'); ?>
[posts.html]
``<html><body><h1>Showing all posts:</h1><?php $query = mysql_query('SELECT * FROM wakaba_beta.posts; foreach($row = mysql_fetch_assoc($query) { echo "<p>Name: ".$row['name']."<br />".htmlspecialchars(str_replace(PHP.EOL,"<br />",$row['comment']))."</p>"; ?></body></html>
Assuming you used a GUI editor like MySQL workbench to create a database called wakaba_beta and a table called posts with 2 columns canned name and comment.
But then you have to add name and subject fields, show an error message if the comment is blank/too short/too long/etc, make a moderation page for deleting posts, make a spam filter, upload images (with artificial intelligence to block cp) etc.
tl;dr - it takes 4 years 2 weeks to make an imageboard