Create a "New Page" for each of those 7 boxes.
Type in each one and publish the pages, each with
their own titles and content.
When you are in admin click on view all pages and scroll
your mouse over the titles. Look at the status bar on the
bottom of your browser to see the URL ... post.php?post=123&action=edit
Write down the post number for each of the 7 pages.
Now, go into the admin part "Appearance, editor" and open the theme
file called "main index template" or whatever your theme calls it.
You can specify on your index template exactly which page to display for
each <div> section ... or each of those 7 boxes.
This is an example, but of course it's not your theme, so yours won't look the same.
I'm showing this to let you see how you can specify the page "post number", that
you wrote down earlier.
In my example, I'm only displaying page 44 in my "feature" box ...
<?php $recent = new WP_Query("page_id=44"); while($recent->have_posts()) : $recent->the_post();?>
<?php the_title(); ?>
<?php the_content(); ?>
<?php endwhile; ?>