Hi Vickie,
Changing the headings individually is slightly more involved because they tend to be sized specifically for the area they appear on the page.
For instance the H1 heading used for the site name has a class of site-title and is 36px, whereas the H1 heading in the main content area is also 36px but has a class of entry-title, so you need to alter the pixel sizing in two places.
Therefore you will need to inspect the headings location, find out what class definition is styling it and then duplicate that styling in your child theme with your altered declarations.
What browser are you using?
I use Firefox with the FireBug add-on installed. This add-on allows you to select a specific part of the web page and inspect what styles are being applied to it. That way it’s easy to refer to the default Twenty Eleven stylesheet, even down to the specific line on which the style occurs, and duplicate it into your own child stylesheet making any alterations accordingly.
Sorry I can’t give you a direct reply but for this theme it’s not simply a case of being able to style all headings en-mass.
All the best,
Tony.