Edit the "About" page

I would like to edit the text on the "About" page. Where is it?

This is my first experience with having code spread out over hundreds of files. Is there an editor for the Mac that you could recommend that could do searches through all these files?

The "About" page should be part of the Simple Pages plugin.

You can edit it by going to the Simple Pages tab in the Omeka admin interface; you shouldn't need to edit any files manually.