Call me stupid, but I don't see a "Pause Menu."

I get to where I can save the game, but there is no "pause" selection. Does the game automatically pause when this menu is open, or is there a separate way to do it?

Okay, but how can I exit the game and return later?

Okay. I give up.

How do I pause the game and how do I save and exit, so I can resume another day. I see very little information in-game or on-line.