Reddit mentions of The Sustainable Vegetable Garden: A Backyard Guide to Healthy Soil and Higher Yields

I did square foot gardening for a couple of years and found it really helpful. More than anything, it gives a solid framework (in a number of respects) by which to learn gardening. I found it to be a great "gateway" gardening technique.

This book is what I learned from.

Square foot gardening is most appropriate when first learning gardening, when learning about plant spacing, companion planting, etc. It isn't a great approach if you're trying to grow a tremendous amount of food, but if you have a few small beds and want to maximize your output from them, it's a great way to go.

Really, the best way to get started is to buy the/a book and read it. It will outline the reason for the method, and all aspects of how it works.

More recently, I'm a fan of John Jeavons' books, in particular How to Grow More Vegetables. It is more useful for when you want to go a bit further with space efficiency and sustainability. His book The Sustainable Vegetable Garden is on the same topic, but is more of an introductory overview.

I'm not sure what else to say, do you have any specific questions about square foot gardening? From your post, I couldn't tell how much you do or don't know about square foot gardening.