Also, auto-installers like fantastico usually require you to install Zen Cart in a subfolder instead of in your domain root, which is where you would normally want the store (immediately accessible to customers). Installing manually allows you to specify the exact location, and really doesn't take any more computer knowledge than auto-installers (unless they create the database for you, leaving you totally in the dark about your critically important database).
You can use your hosting control panel to create the database without knowing anything about how it works, but you will then have a clue about where to look if something goes wrong.