need some info about zen cart

ok now guys i want to edit or chage code in notepad++ but the thing is how do i open the files. I have installed zen cart from cpanel actually from Softaculous and it seats in my cpanel right
so if i want to edit some files how do i open them in notepad++
thanks

Download (FTP) the files to your local drive to make your changes using Notepad++ and then transfer the changed files back to your site.

ok i got that one. but now if i want to edit only one file should i download only that one file or i have to download the whole zencart and then upload the whole thing.
thanks

ok now i got the zencart downloaded from cpanel do my pc and my question is when you modify one file ie. header.php once it is changed on my pc do i upload only that file or i have to upload the whole zencart files
thanks

Det your head around the "Override" system
You only need re-upload the files you change but they should be loaded to folders you create named for your template

https://www.zen-cart.com/tutorials/index.php?article=230
https://www.zen-cart.com/tutorials/index.php?article=143

No, just the file you want to edit.

But it would be a good idea to download the entire Zen Cart fileset to your computer and save it in a convenient place. Then when you want to edit a file, you can just open it from there, edit, save and FTP to your site, which will leave a full backup on your computer with all current changes.

Glenn's advice is absolutely valid... If you have a full "copy" of your files on a local drive, then editing is much safer. Backup the original file on your server, then FTP the edited file(s) to the server. If you have made errors on the edited copy, re-instating the backup will restore all functionality. Then you can try again...