Unzip the download onto your local drive (you don't have to be able to run it locally, you just need to edit the files).
Locate the file you want/need to edit and copy it into a folder for your custom template. Anywhere you see a /classic/ folder, you can create a folder for your custom template. Copy the necessary files from either the /classic/ or /template_default/ folders.
Upload the changed folder/file to where you installed ZC and select the template from your admin under tools->template selection.
To create a very basic custom template (you can build from there), you need:
includes/languages/YOUR_TEMPLATE/english.php
includes/languages/english/YOUR_TEMPLATE/index.php
includes/languages/english/YOUR_TEMPLATE/header.php (to change the logo)
includes/templates/YOUR_TEMPLATE/template_info.php
includes/templates/YOUR_TEMPLATE/common/tpl_header.php
includes/templates/YOUR_TEMPLATE/images/logo.gif
includes/templates/YOUR_TEMPLATE/css/stylesheet.css
Mary Ellen
I came; I saw; I Zenned
Taking over the world... one website at a time
Make sure brain is engaged before putting mouth in gear... or fingers to keyboard.
Holzheimer
Fan Odyssey