This thread was started 40 months ago to gather the most often asked questions/first stumbling blocks for newbies and put them in one place. You can find them in the Tuts/FAQs here (25 articles):
https://www.zen-cart.com/tutorials/i...hp?category=16

Get to know ZC's file structure (you say you have it on your computer). Most customizations will be made to files in the /includes/ folder. Read the articles in the docs folder (that came with ZC) about installation, upgrading, securing your site, etc.

Learn about the template override system. (Search Tuts/FAQs for "overrides"). Print out one of the charts. Here:
https://www.zen-cart.com/tutorials/i...hp?article=143
or here:
http://www.zen-cart.com/index.php?main_page=product_contrib_info&products_id=298

You can view the free templates in action here:
http://(sorry, site offline)/

Be prepared for frustration. There is a learning curve.
But, stick with it. You'll be glad you did!