From Zen Cart(tm) Wiki
To install an addon/mod/contribution, the process typically goes something like this:
- Unzip the zip file contents, retaining the folder structure.
- You'll see that there are "includes" and sometimes "admin" folders, with folders underneath.
- If you look at your Zen Cart site files, you'll see a similar folder structure.
- Copy the extracted files and folders to the matching folder structure on your server ... according to the instructions contained in the readme file that comes with most mods.
- Follow any other instructions that came with the mod.
****IMPORTANT**** BE SURE TO MAKE BACKUPS OF ALL SERVER FILES AND YOUR SERVER DATABASE BEFORE INSTALLING ANY MOD ****
*** IT IS ALWAYS WISE TO TEST EVERY MOD ON A ***TEST*** COPY OF YOUR STORE, and not directly into a live store, unless you're completely confident that you won't break anything.