I see a lot of users with the possibility to a 'theme editor' in their appearence menue, but I dont have that on my account?
WordPress.com does not offer the option to edit theme code directly, so the theme editor you're thinking of is not available on WordPress.com and you must be looking at posts or tutorials about WordPress.org blogs. See http://support.wordpress.com/com-vs-org/ to learn about the differences.
At WordPress.com, the Custom Design upgrade gives you the option to add or replace CSS. You can do a ton with CSS only, but if you're looking to change the structure of a blog, then you'll want to switch to a WordPress.org setup which gives you complete control over the code including the theme editor option you were looking for. There are pros and cons to each setup, check out that link above to learn more, and reply back here if you still have questions after that.
For more information about the Custom Design upgrade on the WordPress.com side, see these links:
Regarding moving the footer widgets in the Balloons theme from the side to the right on WordPress.com, some people have figured out how to do it with CSS only. Her is an example:
To test that, add the code to your Appearance → Custom Design → CSS page and click the Preview button.