FOR THE TEMPLATE FILES
Open up activity/index.php (one of 13 files transfered by the template pack process to your on demand theme folder)
At top, replace
<?php get_header() ?>
<div id="container">
<div id="content">
with
<?php get_header(); ?>
<div id="content">
<div id="content-inside">
<div id="post-container">
<div id="posts-page">
Right under that, replace heading h3 with h2
<h3><?php _e( 'Site Activity', 'buddypress' ) ?></h3>
with
<h2><?php _e( 'Site Activity', 'buddypress' ) ?></h2>
At the bottom of the page, replace
</div><!-- #content -->
</div><!-- #container -->
<?php locate_template( array( 'sidebar.php' ), true ) ?>
<?php get_footer() ?>
with
</div> <!-- posts-page -->
<?php get_sidebar(); ?>
</div> <!-- post-container -->
</div> <!-- content-inside -->
</div> <!-- content -->
<?php get_footer(); ?>
Then you do this for the next 12 template files.