Upgrades vs overrides

I am a little worried. I think I have created correct folders so they dont get copied over should I upgrade but I am not sure if I have done everything right.

Is there need to worry and re-check or can I just not upgrade? Will not upgrading effect the functionality of my site in the future?

I am only wanting a basic easy system...nothing fancy!

Not upgrading/updating will deprive you of all the enhancements and improvements the Zen Cart team works so hard to make. If you've set up your overrides correctly (basically, making your own folders and storing the files you change in them), you shouldn't have a problem upgrading/updating. Once you install the upgrade/update, it's a matter of comparing your customized files to the latest version of the same files.

If you're worried that you may have some changes in core files instead of overrides, compare your site's files with the files in a fresh copy of Zen Cart, using a tool like Winmerge. That will show you if any core files are different, and you can copy any that are to your overrides.