how to include Java and css in a post ?

If it’s a PAGE, not a post, make a custom template

http://codex.wordpress.org/Pages About half way down the page, look for “Creating Your Own Page Templates”.

This post has some intructions, too

html?
You’re working with php here, captain.

Anyway, after looking at the tabber code, I think you can just add it in the header.php file of your theme.

Find </title> in your header.php
add this line BELOW it:
<script type="text/javascript" src="replace this with the path to your tabber.js file"></script>

then find </head>
add this ABOVE it:
<script type="text/javascript">document.write('<style type="text/css">.tabber{display:none;}<\/style>');

Then just make a page as normal through the dashboard

<div class="tabber">

     <div class="tabbertab">
	  <h2>Tab 1</h2>
	  <p>Tab 1 content.</p>

     </div>

     <div class="tabbertab">
	  <h2>Tab 2</h2>
	  <p>Tab 2 content.</p>
     </div>

     <div class="tabbertab">

	  <h2>Tab 3</h2>
	  <p>Tab 3 content.</p>
     </div>

</div>

If you were to make a page template, you would need to replace “<?php get_header(); ?>” with all the text in your header.php file and paste it into that new template (erasing <?php get_header(); ?>), then add in the tabber.js code line and the document.write code line in the header code you just pasted in (like I explained at the beginning). Which is probably why it didn’t work.

You may want to try the Tabber Tabs Widget Plugin.