I was wondering if it is better to buy Wordpress and then Studiopress just to change the theme.
You were looking at Wordpress.COM, which is the hosted version of Wordpress.
Studiopress sells themes for the self-hosted version of Wordpress available at wordpress.org - which you install yourself after buying hosting and a domain. Also the wordpress software itself is FREE.
When you were looking at wordpress.COM (which is different) you were looking at the upgrades for the version hosted by them. They do not allow you to run your own ads or install your own plugins or themes.
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.