Hi bluellipse,
When customising an existing WordPress theme, it is advised to create a child theme.
A child theme is, essentially, a theme that makes use of the files of another theme and the styling (and any overridden functionality) of your new theme.
Creating a Hybrid child theme is easy. The steps are as follows:
1. Unzip Hybrid into your themes folder.
2. Create a new theme folder.
3. Inside your new folder, create a style.css file and paste the following code at the top, changing the areas in capitals:
/**
* Theme Name: YOUR_THEME_NAME
* Theme URI:
* Description: A_DESCRIPTION_OF_YOUR_THEME
* Version: 0.7.1 (keep this the same as Hybrid, for your reference)
* Author: YOUR_NAME_HERE
* Author URI: http://your-url.com
* Tags: YOUR_TAGS_HERE
* Template: hybrid
*/
This essentially tells the system: "This is my new theme, and if you can't find a file in here, look in hybrid for the file." This is the concept of child theming. Thus, the original Hybrid theme is preserved, and your changes are separated into your own theme.
If you wish to override specific functionality within Hybrid, there are a selection of filters and hooks that can be modified, along with the extensible nature of the Hybrid theme.
I hope this helps. :)
There's also an excellent community over at the Theme Hybrid website: http://themehybrid.com/support/ :)
All the best,
Matty.