Making a simple shopping cart application, if that's truly what you need, isn't too difficult but takes quite some time to produce properly. Employing a design
pattern, like MVC, for your application is essential in my opinion.
Before you do anything, I would spend a little time thinking about your scope and just how big this application needs to be. What I mean by that is... do you want a simple product catalog and be able to add items to a cart? Or do you also want users to register accounts, be able to log in, view past purchases, etc.? Will items ever go on sale? Is inventory going to be maintained?
Working out the logistics of your application is important before you get too deep. As well, it will help you figure out what you need to look for in terms of tutorials and other resources as you go along.