If you go here: fiddly-bits . com/ shop (take the spaces out for a proper URL), what you see is based on a template I found online and purchased so I didn't have to credit the designer; all I used is the .css file. And I didn't know .css *or *.php when I started this.
I just upgraded and although I haven't done an exhaustive check of every little jot and tittle, my site looks the same, and still has the same lame products I need to change out, and a fake 'order' takes me to Paypal and sends me back to my site. All works as expected so far.
The instructions are kind of obscure; here's what I did:
I backed up my store directory to my local computer.
I unzipped the files for the install to my local desktop.
On the server, I renamed my admin directory from the 'secure' name I gave it back to 'admin'. You get errors if you don't do this and a pox on the person who forgot to mention it in the setup instructions.
I copied all the files from my desktop (minus a few folders like media and docs I didn't use) to the server with FileZilla, putting them under the directory tree where they belong. I'd already used WinMerge to compare the files, and the majority of the changes are understandable and don't impact site configuration, AFAICT; I'm not a programmer, but changes from GETs to POSTs account for a lot of the changes, as well as some changes in SQL queries and the like.
I then got the URL of the zc_install directory and ran the install from there. Pretty easy; mostly a 'click the big button' kind of thing. It lets you know if you have to change your configure.php files to make them writable or do other preparatory things. After upgrading, I renamed the admin directory back to the 'secure' name, and modified permissions on the configure.php files back to what they were before I got started on the upgrade.
I could get into the store as well as the admin control panel from that point. It's not that difficult; if I can do it, I feel confident that just about anybody can because although I do have some familiarity with computers, having done network support for several years, the process of installing Zen Cart was new to me, and if I can make it work, so can you.
Just remember to back up first. :cool: