I am baffled by the sorting logic in ZC. (1.3.9h)

I'm trying to control the order in which my customers view the products.

On the product page I see a "sort order" box. And in the admin section, I see a couple of different spots where I presumably can control sorting, but nothing seems logical to me.

Can someone point me to a FAQ or tutorial on how I go about this?

Thanks,

John