There are a few good books on the topic: "Root Cellaring" by Mike and Nancy Bubel is a classic. Also "The Complete Root Cellar Book" as well as half a dozen or more on Amazon. I have and would recommend the first, but there are a lot more out now and many of those may be as good or better.
Lots of possibilities. From insulating and venting part of your unheated basement, to burying cans/barrels/etc, to digging and building a cellar from scratch. It is useful (IMO) to read a book or two and talk with some locals who have done it in your area and then decide. Solutions are similar everywhere, but what works in one climate won't necessarily do so everywhere.
I did "play around" with a buried chest freezer, prior to building a "real" root cellar" on our property. Dead chest freezers are easy to come by, and if you get one with a metal interior should be rodent and insect proof. It did need insulation up top otherwise things would start freezing in Jan, but at 8000+' in the Rockies it may be colder and windier here than your locale. Anyway a chest freezer type setup or the like might be a fairly easy way to test the waters and see what works and doesn't for you.
Be advised, managing food storage in a root cellar is a learned experience. There's a lot more to it than buying frozen food in the supermarket and throwing in the freezer when you get home. In addition to getting the cellar's building details right, one needs to know how to manage it, get it cool quickly in the fall, keep it from getting too cool or wet, and keeping it from getting warm in the spring. There also is some learning as to what varieties of things to grow for storage and how to grow and harvest them properly. None of these are that hard, it's just that we need to relearn a whole lot of knowledge that was just common place in our grandparents or great-granparents time.
Good luck with your project.