Creating my own theme

Hi all,

I'm quite new to drupal, I've been reading webpages all week to feel more comfortable with the way the administration works. Now I started creating my own theme. I have some really basic PHP knowledge. I have made my design in valid XHTML and CSS, no tables. I hae set up a test site on my own pc.

I copied the bluemarine theme dir and started with removing everything from the page.tpl.php file. Than I pastd my html in and copied lines of php code I felt necessary. This way I managed to get it about the way I wanted it to look. I copied my css into the style.css file.

I'm stuck now however: by looking at the source (mainly the class and id selectors) I think the node.tpl.php is used for showig the frontpage content, but I have no idea how drupal knows where to place it.

I have this part of code in my html on page.tpl.php:

<div id="center">

	<?php print $breadcrumb ?>
		<h1><?php print $title ?></h1>
		<?php print $tabs ?></div>
		<?php print $help ?>
		<?php print $messages ?>
		<?php print $content; ?>
		<?php print $feed_icons; ?>
	
</div>

I have no idea what everything means, but somehow the node.tpl.php file seems to be placed right after this div, while I would like to place it inside this div. Could somebody point me at a good manual for theming my own site, all the ones I found so far didn't go quite deep enough for me.

Thanks in advance!