right, thats the next step. if you've added it to the page then publish the page and view it.
open another tab in your browser so you can edit the template file my_custom_page.php
so appearance -> themes -> editor. select the my_custom_page,php file in the list on the right and it should open the code editor in the main panel.
you're looking for php shortcodes like
<?php get_sidebar(); ?>
you can either delete these (not advisable) or comment them out by adding
inside the php tags like this
<?php /*get_sidebar();*/ ?>`
do the same for things like the footer. not too sure about the header title, what theme are you using?