Rippetoe has a good clear description in Starting Strength which I found useful. Crib notes version as follows:
Create a shelf on your upper back (superman chest and fully retracted scapulae). This should bear all the weight of the bar, your arms are just pressing the bar into your back to keep it on the shelf. Grip width will vary based on comfort and flexibility, but your forearms should be generally perpendicular to the bar (snatch grip sounds to wide to achieve this unless you have a funky build). Use a thumbless grip on the bar and keep your wrists locked and aligned with your forearms, not pronated. Instead of thinking about holding the bar up with your arms focus on rotating your elbows back and up, this will drive the bar into your back and keep it firmly on the shelf.
I don't have the book in front of me so apologies if I missed or distorted anything.