I have found the code which should sovle my problem of only showing top-level pages in on the front page, but not sure how to enter it into the Sidebar code template. I found the line in which it should go, but by pasting it in there I made the sidebar dissapear!
The code is: 'sort_column=menu_order&depth=1'
and it should go in the line: <?php wp_list_pages('title_li=<h1>Pages</h1>'); ?>
I am using the Aurora theme...