Themes are only available starting with Openmeetings 2.x.
There are also more general client side configuration like port configuration. Those configs are stored in the public/config.xml
To modify default theme used by OM please open following file in the SVN:
and follow to link following "To view and modify this theme, visit" text in css comments
Or if you already installed OpenMeetings on your machine at:
The file contains border, background and font color definitions as well as paths to icons that are loaded at runtime.
You can change the theme at runtime and just reload the browser (eventually clear the browser cache) to see updates based on modification in your theme.
All other elements might be styled by modifying CSS files in /webapps/openmeetings/css folder