Alas, the ultimate noob of Zen Cart has quite possibly arrived!

I knew some HTML and some CSS. Remember that the operative word here is KNEW. Quite a few years ago, I was interested in such things and was somewhat good at it. But, as years passed, the knowledge diminished as fast as I learned it. I now stick to tutorials created by those who want to lend a helping hand to those who are completely clueless about HTML and CSS and PHP and etc etc etc.

Anywho, all that aside... Does anyone know of a Zen Cart tutorial or FAQ that literally spells out which line in a Stylesheet corresponds to what is being modified on the website itself? If not, which stylesheet should I look into in order to change the color schemes and logos of all of the pages in my store catalog?

I ask that you please forgive my lack of knowledge for Zen Cart and its customization processes. Any help would be greatly appreciated.

Thanks.