Okay, So I have very little background in PHP or JS or anything other than HTML and CSS basically.

Here goes nothing
It seems ive bitten off more than I can chew with my latest project, as I've told someone that I would take the time to figure out on how to add a shopping cart to his website. But the problem is ive never built a shopping cart, I have no experience with databases and I don't know how to code PHP. I am a very fast learner and if I get pointed in the right directions I am positive I can pull it off.

What I need: A shopping car that I don't need 4-5-6 different programs to operate. Id be more comfortable opening it with Notepad or something similar. If I were to do this step by step. What should be the first thing I do to make myself a shopping cart. Could someone provide me with the basics so that I can do some research on exactly what needs to be done?

Also, (I know im far from this step but) Id like to have a drop down menu to select the product. I know how to make a drop menu... but I don't know how to point it to a specific place in the Database.