How to edit the All Rights Reserved on my website

Try editing your current theme’s footer.php template file.

I don’t know what I’m trying to edit. I don’t see anything in that file that says 2011.

Do not edit the Twenty Eleven theme. It is the default WordPress 3.2 theme and having access to an unedited version of the theme is vital when dealing with a range of site issues. Create a child theme for your changes. Once your child theme is active, we should be able to help with the customisation.