I believe you are entitled to Genesis plus a child theme of your choice.
It is not really upgrading the site to a new theme - you just activate the new child theme, much like switching over to a new theme in WordPress.
These forums were CLOSED to new posts on November 19th, 2012. New forums are here: http://www.studiopress.com/forums/
and you will need to SIGN UP AGAIN.
If you need assitance with setting up your theme, go to http://my.studiopress.com/
and read the SETUP links or the TUTORIALS link on the side tab.
If you need Account Assistance
, file a help desk ticket at the same location.