Trying to change 2 column template to 3 column

Hi-

I am trying to change this 2 column template to 3 column template, but so far, I am having difficult time modifying the files…

Is there a basic 3 column code that I can just take and use?

I have created sidebar_l.php and sidebar_r.php and I have:

<?php get_header(); ?>
<?php include(TEMPLATEPATH."/sidebar_l.php");?>

<?php /* These tell the user what type of archive they're on. You can easily customize the messages here. They use _e("...") to make them easily translated into other languages. This should help in localization a bunch. This also reduces the need for a page for all these types of archives. Unless you're using a very different setup on each one, this way seems to be much lighter on file sizes, markup, work, etc... */ ?>

<?php // This is the main loop. Body content is passed in through this code. ?>

<?php if( $posts ): foreach ( $posts as $post ): start_wp(); ?>

<h1><a href="<?php the_permalink(); ?>" title="Permalink for <?php the_title(); ?>"><?php the_title(); ?></a></h1>
<?php // Spit out the header with a link to the article. ?>

<?php the_content(); ?>
<?php // The content, and what to use if  there is a <!-- more --> extension. ?>

<p class="meta"><?php the_time("F j, Y"); ?>. <?php the_category(', '); ?>. <a href="<?php comments_link(); ?>"><?php comments_number(); ?></a>.<?php edit_post_link('Edit'); ?></p>

<?php // The information related to the post, such as the date, category, and comments. ?>

<?php endforeach; // End looping ?>

<p><?php posts_nav_link('','','Older Entries') ?> <?php posts_nav_link('','Newer Entries','') ?></p>
<?php // Go to previous and newer posts links. This is needed because WordPress by default limits the number of posts you may have in the loop.?>

<?php else: ?>
<?php if ( is_search () ) { ?>
<p><?php _e('Sadly however, no results were found. Please try searching again.'); ?></p>

<form method="get" id="searchform" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<input type="text" value="<?php echo stripslashes($_GET['s']); ?>" name="s" id="s" length="20" />
<input type="submit" id="searchsubmit" name="Submit" value="<?php _e("Search"); ?>" />
</form>

<?php } else { ?>
<p><?php _e('Sorry, no posts matched your criteria.'); ?></p>
<?php } endif; ?>
<?php include(TEMPLATEPATH."/sidebar_r.php");?>
		<div class="clear"></div>
<?php get_footer(); ?>

and it looks like this:

https://www.theparisapartment.com/blog/

I will fix the graphic, but it’s showing both side bar twice and the main content is not showing up in the middle… ??

any help would be very appreciated. Thank you so much in advance!